Human Reproduction Update

Human Reproduction Update Advance Access originally published online on May 26, 2005
Human Reproduction Update 2005 11(5):495-512; doi:10.1093/humupd/dmi018

This Article Abstract FREE Full Text (PDF) All Versions of this Article: 11/5/495    most recent dmi018v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Archive Download to citation manager Search for citing articles in: ISI Web of Science (19) Request Permissions Google Scholar Articles by Melby, M. K. Articles by Kaufert, P. Search for Related Content PubMed PubMed Citation Articles by Melby, M. K. Articles by Kaufert, P. Social Bookmarking          What's this?

© The Author 2005. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oupjournals.org

Culture and symptom reporting at menopause

Melissa K. Melby^1,2, Margaret Lock^3,5 and Patricia Kaufert⁴

¹ Department of Anthropology, Emory University, Atlanta, GA, 30322, USA, ² Laboratory of Public Health Nutrition and Epidemiology, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo, 156-8502, Japan, ³ Department of Social Studies of Medicine, McGill University, 3647 Peel Street, Montreal, Quebec, H3A 1X1 and ⁴ Community Health Sciences, 2110E Med Serv Bldg, University of Manitoba, Winnipeg, Canada

⁵ To whom correspondence should be addressed. Email: margaret.lock{at}mcgill.ca

	Abstract

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
The purpose of the present paper is to review recent research on the relationship of culture and menopausal symptoms and propose a biocultural framework that makes use of both biological and cultural parameters in future research. Medline was searched for English-language articles published from 2000 to 2004 using the keyword ‘menopause’ in the journals—Menopause, Maturitas, Climacteric, Social Science and Medicine, Medical Anthropology Quarterly, Journal of Women's Health, Journal of the American Medical Association, American Journal of Epidemiology, Lancet and British Medical Journal, excluding articles concerning small clinical samples, surgical menopause or HRT. Additionally, references of retrieved articles and reviews were hand-searched. Although a large number of studies and publications exist, methodological differences limit attempts at comparison or systematic review. We outline a theoretical framework in which relevant biological and cultural variables can be operationalized and measured, making it possible for rigorous comparisons in the future. Several studies carried out in Japan, North America and Australia, using similar methodology but different culture/ethnic groups, indicate that differences in symptom reporting are real and highlight the importance of biocultural research. We suggest that both biological variation and cultural differences contribute to the menopausal transition, and that more rigorous data collection is required to elucidate how biology and culture interact in female ageing.

Key words: culture / local biology / menopause / methodology / symptom reporting

	Introduction

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
Cross cultural research on menopause has its foundations in an anthropological study of menopausal women in Northern India (Flint, 1975) and in a series of surveys sponsored by the International Health Foundation (Boulet et al., 1994) under the leadership of Dr Pieter Van Keep, who set out to document variations among countries in women's reporting of the menopausal transition. These surveys collected information on general health and on attitudes towards ageing and the menopause, but their primary focus was on age at menopause and menopausal symptom patterns. Since these early surveys, interest in the relationship between culture and the menopausal experience has broadened, but a focus on menopausal age and subjective reporting of symptoms remains central.

Over the past decade there have been several comprehensive reviews on the subject of culture and menopause, many of which have focused on symptom reporting (Flint and Samil, 1990; Lock, 1998; Gold, 2000; Obermeyer, 2000; Avis et al., 2001; Collins, 2002). Virtually all of the research cited in these reviews has been motivated by one of two rather different objectives. In the first approach, taken by the majority of researchers, an assumption is often made that biological changes associated with menopause are, in effect, universal, and that variation in the subjective experience of menopause, notably in what counts as menopausal symptoms and how they are reported, can be largely explained by language differences, culturally shaped expectations about the menopausal transition, and more generally by concerns about female ageing and associated changes in social roles (Boulet et al., 1994; Obermeyer et al., 1999; Sommer et al., 1999; Adler et al., 2000; Zeserson, 2001). In much of this research, culture is equated in an unproblematic way with nationality, and is inserted into analyses as an independent variable.

Differences in symptom reporting among women are suggested to be artefacts of differences in symptom sensitivity or a tendency to under-report, due to lack of education or else embarrassment (Boulet et al., 1994). On the other hand, researchers who acknowledge that differences in symptom reporting may indeed reflect variation in the menopausal experience (Kaufert, 1984, 1990; Kaufert et al., 1988; Avis and McKinlay, 1991; Zeserson, 2001) remain concerned about methodological differences that make comparison difficult and chronic weaknesses in research design and reporting including: (1) instrument (questionnaires administered by interview or mail); (2) recall time frame (retrospective reporting of age at menopause and symptom recall from 2 weeks to 1 year or ‘ever’, particularly problematic as symptom recall of over 2 weeks is likely to be inaccurate); (3) menopausal status analysis categories (inclusion of surgical menopause, assignments of perimenopausal status); (4) choice of symptoms and focus on ‘menopause’ versus ‘midlife health’; and (5) language (complexity involved in translating medical terminology and everyday terms that describe bodily symptoms).

The second, less common approach, is one in which biological and socio/cultural variables are assumed to interact in complex ways that are as yet rather poorly understood (Lock, 1993; Martin et al., 1993; Avis et al., 1997, 2001; Collins, 2002). These ‘biocultural’ analyses (Beyene, 1986) seek explicitly to overcome the limitations imposed by a methodology in which a marked duality between biology and culture is structured into the project. Our position is that differences in symptom reporting are not epiphenomena, layered over the facts of biology, but rather result from the interaction of biological and cultural influences on women's menopausal experience. In the latter part of this paper we lay out a theoretical framework for biocultural research on menopause, discuss recent research findings on the role of phytoestrogens in Japanese diets and their effects on symptom reporting at menopause as illustrative of the complexity that confronts researchers, and provide examples of research that should serve as models for future research.

Before proceeding further, a cautionary note is necessary in connection with the concept of culture. In the global situation with which we are confronted today, culture must be recognized as an entity that is fluid and not necessarily bounded by geographical, national, or ethnic demarcations. It is important to actively inquire about self-assigned cultural affiliation(s) and what this means for individual women. Moreover, it is a mistake to assume that everyone participates equally in the values associated with the dominant culture with which they formally identify themselves—this too needs to be teased apart. For example, although it has been postulated that urban women, with exposure to North American culture's valuation of youth, would have more negative attitudes toward menopause, a recent study of Iranian women found the opposite. The authors suggest instead that rural women in Iran placed higher priority on fertility (and thus have more negative attitudes toward the end of menopause) than did their urban counterparts (Khademi and Cooke, 2003). Research of this kind demonstrates that the influence of cultural expectations on attitudes toward menopause (and thus indirectly on menopausal experience) may be quite complex.

An initial decision to conduct a Cochrane style review (Alderson et al., 2004) had to be discarded as too few studies satisfied our criteria of having a large sample randomly selected from the general population, a well-validated instrument to measure depression and general health status, and sufficient power to detect significant differences in symptom reporting between women from different ethno-cultural communities. Adopting a more open and less restrictive approach to reviewing the literature on symptom reporting at menopause, we excluded studies based on small clinical samples, those with a primary focus on the use of HRT, and those that had not discriminated between women with ‘natural’ menopause as distinct from menopause that was surgically induced. Reviewing the European and North American literature, we focused on studies set up to examine differences in symptom reporting between women from different racial/ethnic groups or that had examined the relationship between menopausal symptom reporting and cultural variables. [The Study of Women's Health Across the Nation (SWAN) is a prime example of an American study committed to recruiting women from different racial/ethnic communities and to exploring the impact of cultural differences on symptom reporting.] To ensure that our review of research done outside Europe and North America was complete, we first compared our list of studies against those included in two very comprehensive reviews on culture and menopause (Obermeyer, 2000; Collins, 2002) on the relationship between culture and symptom reporting. As their reviews dealt only with material published up to the year 2000, we then used Medline to search the journals Menopause, Maturitas, Climacteric, Social Science and Medicine, Medical Anthropology Quarterly, Journal of Women's Health, Journal of the American Medical Association, American Journal of Epidemiology, Lancet and British Medical Journal for any additional articles on the menopausal symptom experience of women living outside North America and Europe that might have been missing from our lists and that were published in 2000–2004.

This paper is divided into four parts: Part I summarizes the factors that have been shown by various studies to contribute to differences in the menopausal experience. This is followed by a review of the major problems and challenges that have arisen as menopause researchers have tried to transfer to other settings definitions and methodologies initially developed in North America and Europe. Part II comprises a review of research on age and vasomotor symptom reporting published in the last few years that combines a systematic examination of socio/cultural variables with documentation of biological variation. In Part III we set out findings from biological anthropology and reproductive ecology that highlight the way in which biological variation must be taken into account in addition to cultural differences and then in Part IV highlight several cross-cultural studies including the authors' research in Japan and North America in order to demonstrate the importance of using a multidisciplinary, longitudinal approach to researching menopause.

	Part I: Factors contributing to variation in the menopausal experience

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
Comprehensive reviews that cover research on the relationship between culture and menopause show without exception that the socio/cultural organization of the course of life in specific geographical locations profoundly affects the meanings and experience of menopause (Gannon, 1985; Beyene, 1989; Du Toit, 1990; Flint and Samil, 1990; Lock, 1993, 1998; Obermeyer, 2000; Avis et al., 2001; Collins, 2002). Factors hypothesized to play a role in the experience of menopause (and quality of life during this period) include: culturally-influenced behaviours such as diet (Albertazzi et al., 1998; Mei et al., 2001; Nagata et al., 2001a,b; Messina and Hughes, 2003), smoking (Whiteman et al., 2003) and exercise (Dennerstein et al., 1993); cultural attitudes towards and expectations about the menopause (Martin, 1988; Avis and McKinlay, 1991; Davis, 1997; Sommer et al., 1999), which can be heavily influenced by medicalization (Kaufert and Gilbert, 1986; Bell, 1987; Kaufert and Lock, 1997; Sievert, 2003); meanings assigned to menopause, such as whether it is recognized as natural and normal, deviant, or as an illness (Estok and O'Toole, 1991); previous symptomatology and prior health condition (Avis et al., 1997); past or current reproductive health (Collins and Landgren, 1995); mother's experience of menopause (e.g. hot flushes) (Staropoli et al., 1998); attitudes toward childrearing and women's roles (Sanchez Perruca et al., 1989); marital status (Avis et al., 2004); relationships with husbands/partners and their attitudes toward symptoms of menopause (Robinson, 1996); social support (Berg and Taylor, 1999) and the extended family (Rousseau and McCool, 1997); social status, socio-economic status (Avis et al., 2003), education (Dennerstein et al., 1993; Avis et al., 1997), career and religious beliefs. For example, many women may not seek medical assistance because they believe that menopause, like puberty, involves natural changes that are part of development and ageing (Woods and Mitchell, 1999). With the support of healthy lifestyles, social support of friends and family, symptoms are often manageable and thus medical intervention may not be necessary (Hvas, 2001; Hvas et al., 2003).

However, culture, in the form of lifestyle choices (e.g. diet, reproductive behaviour, smoking) can also modify the underlying biology of the menopausal experience. Using a lifespan approach, Leidy has argued that although variation in age at the last menstruation is confined to a narrow spectrum, it is nevertheless significant and is influenced by family history. She notes: ‘Genetically, parents pass to their daughters the parameters for number of oocytes and/or rate of atresia. Behaviourally, a mother's activity while pregnant affects the ovarian store her daughter possesses at birth. From birth until menopause the environment and behaviour of the individual affects her own ovarian stores’ (Leidy, 1994). Diet, age at menarche, reproductive history, use of oral contraceptives or other medication and smoking history—to name the most obvious variables—are all implicated in age at menopause and also potentially in symptomatology. In other words, it is important to consider how culture affects the body over the entire lifespan and not simply focus on the brief time period around the end of menstruation. Interactions among genetics, environment, culture and aspects of everyday life, including parity, socio-economic status (Avis et al., 2003), education (Dennerstein et al., 1993; Avis et al., 1997), reproductive hormones and history (Whiteman et al., 2003), smoking, BMI and exercise (Schwingl et al., 1994), contribute over the lifespan to the production of bodies that eventually become menopausal, with significant differences among them.

Methodological issues in menopausal research

The definition of menopause used by the majority of researchers and clinicians as well as by most women in North America, Europe and Australasia, equates menopause with the end of menstruation. Seen in a broader historical context, this definition is relatively recent. The changes associated with ageing and menopause vary both historically and across cultures (Lock, 2002). The current medical model emerged in the mid 20th century, is not accepted everywhere, and does not ‘fit’ well with local accounts of female midlife, professional and popular, in most parts of the world. Rather than being defined by a single event—the last menses—the menopausal transition is understood as a process, part of the phenomenon of ageing, and is associated with both social and biological changes.

There can be no argument that female reproductive senescence is universal and that the last menstrual cycle takes place in a relatively narrow range of ages [although ethnic and environmental differences have been noted, suggesting that even this fundamental transition may be influenced by culture (Bromberger et al., 1997) and environmental factors (Gold et al., 2001; Ku et al., 2004), as well as genetics]. Once the focus of attention is shifted to symptom reporting at menopause, data collection and the interpretation of findings become exceedingly complex. For example, it is not sufficient to ask if a woman is still menstruating. One must establish why menstruation has ceased: whether due to surgery, medications or chemotherapy; co-morbidity; chronic stress or shortage of food (as is the case in many developing countries); pregnancy and/or lactational amenorrhoea.

Research findings from many locations indicate that the majority of women pass through the menopausal transition with relatively little or no discomfort (Lock, 1993). Survey research in the USA and Canada with large samples of women aged 45–55 who are representative of the general population adds substantial support to this finding (McKinlay et al., 1992; Kaufert et al., 1998a,b). In a review, Obermeyer (2000) notes that while few women report major, long-lasting discomfort, paradoxically, in virtually all societies that have been investigated, the overall image of menopause is associated with unpleasant symptoms. Findings also show that people everywhere attach both positive and negative meanings to the end of menstruation, although few studies inquire about positive aspects (Hvas, 2001). Qualitative research makes clear the unavoidable ambivalence so often associated with the end of reproductive life, the implications of which vary enormously depending upon local attitudes towards ageing in general, older women in particular and their place in society.

	Part II: Review of recent research on age at menopause and symptom reporting

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
Age at menopause

While the main focus of this review is symptom reporting at menopause, much research has focused on age at menopause (Gold et al., 2001), which may influence long-term disease risk and mortality in women (Jacobsen et al., 2003), and thus the experience of menopause. The last 5 years have seen the publication of several large surveys from outside English-speaking Western countries including several countries in Asia and the Middle East. The highest reported mean menopausal ages were reported in Italy (50.9 years, n=4300) (Meschia et al., 2000), Iran (50.4 years, median 49.6 years, n=8194) (Mohammad et al., 2004) and Slovenia (50.4 years, median 52.03 years, n=58) (Sievert et al., 2004). Mean menopausal ages between 47 and 50 years were reported for the following populations: Koreans living in Korea (49.3±3.5) (Ku et al., 2004), Lebanese (49.3 median) (Reynolds and Obermeyer, 2001), Singaporean (49.1) (Chim et al., 2002), Korean emigrants to China (48.9±3.1) (Ku et al., 2004), Greek (48.7±3.8) (Adamopoulos et al., 2002), Moroccan (48.4 median) (Reynolds and Obermeyer, 2003), Mexican (48) (Malacara et al., 2002), Han Chinese in Taiwan (48) (Fuh et al., 2001) and Turkish (48±4.2) (Ozdemir and Col, 2004). The lowest reported average menopausal age came from Turkey (45.8±4.2) (Biri et al., 2005). Asia and the Middle East are over-represented in published reports of the last 5 years, with little data from Latin America or Africa. Most studies report mean age, but a few report median age. Sample size and length of time post-menopause (i.e. retrospective reporting of menopausal age) may be severe limitations in many studies. Most of the reviewed research equates culture with nationality, and thus in reporting the results we also reproduce this problematic limitation. The large SWAN study, while conducted solely in the USA, includes five ethnic groups and has studied associates of age and menopause and many factors (Gold et al., 2001). In the above studies the following factors were positively associated with age at menopause (Table I): age at menarche, menstrual bleeding length (>5 days), BMI, marriage and parity, prior oral contraceptive use, mother's and sister's age at menopause. The relationship between age at menopause and factors such as education and rural–urban residence varied by population. Smoking was consistently negatively associated with age at menopause. Socio-economic status, unemployment and history of heart disease were also negatively associated with age at menopause in several studies.

View this table: [in this window] [in a new window]   Table I. Factors influencing age at menopause identified in recent studies (2000–2004)

 

Menopausal symptom reporting

Identifying the symptoms that are most bothersome and troublesome to women during the menopausal transition and distinguishing between those that are due to hormonal changes as opposed to having ageing- or socially-related aetiology, are crucial for researchers and for clinical care and public health policy. Women often report symptoms such as anxiety and headaches at menopause, but such reporting is by no means limited to women alone, as one Dutch study showed (van Hall et al., 1998). Not only do middle-aged men report similar symptoms at approximately the same rates as do women but so do younger and older women. In Japan, the symptom reported more than any other during the perimenopause is shoulder stiffness (Lock, 1993), but this symptom is reported by a similar percentage of men, as well as younger people (Fujita et al., 2000). The end of menstruation is an event of considerable significance for some women, and a tendency exists to attribute physical and psychological symptoms of all kinds to this experience (Bromberger et al., 2001). This is not to deny that feelings of anxiety and depression are real and significant, but such symptoms are usually secondary to the end of menstruation, and can be associated with broader familial and socio/cultural events, often of long duration, or with concern and stereotypes about the menopausal experience that are conflated with the end of menstruation. Today, for example, as a result of the wide public dissemination of medical literature about the perimenopause it is common for women in Europe and North America to believe that they will suffer memory loss at menopause. While estrogen is essential to neurological functioning (Silva et al., 2001), claims that memory loss is directly associated with lowered estrogen levels at the end of menstruation have not been substantiated (Kesslak, 2002; Kritz-Silverstein and Barrett-Connor, 2002); moreover both men and women experience memory impairment as they age so that this can be regarded as ‘normal’.

Which symptoms constitute menopausal symptoms vary widely between populations and studies (Dennerstein et al., 2002). For example, several studies carried out in Thailand generated four different symptom lists and thus different constellations of menopausal symptoms (Table II). Symptoms included in the Thai checklists range from eight vasomotor and psychological symptoms (Chompootweep et al., 1993) to 17 vasomotor, physical and psychological symptoms (Chirawatkul and Manderson, 1994), and some studies also included urinary tract and vaginal symptoms (Sukwatana et al., 1991; Punyahotra et al., 1997), fracture (Sukwatana et al., 1991) and lack of sexual desire (Chirawatkul and Manderson, 1994). A meta-analysis of 7 factor-analysis studies has shown that vasomotor symptoms appear to be robustly associated with the menopausal transition (Greene, 1998), although older men have also been reported to experience hot flushes (Spetz et al., 2003). Drawing on findings from the SWAN in the USA, Avis et al. (2001), using factor-analysis, have shown that vasomotor symptoms consistently cluster together separately from psychological and psychosomatic symptoms. The SWAN is the latest and largest of epidemiological studies of the menopause, following the Massachusetts Women's Health Study (Avis and McKinlay, 1991; McKinlay et al., 1992), and the Healthy Women Study which included Caucasians and African-Americans (Matthews et al., 1994a,b; Bromberger et al., 1997), and other studies (Samsioe et al., 1985; Dennerstein et al., 1993; Schwingl et al., 1994; Collins and Landgren, 1995; Kuh et al., 1997; Staropoli et al., 1998; Wilbur et al., 1998).

View this table: [in this window] [in a new window]   Table II. ‘Menopausal symptoms’ included in several studies carried out in Thailand

 

The rewards in terms of increased understanding of the menopausal transition are gradually becoming evident as a result of a series of papers emerging from the SWAN, a longitudinal, multi-site, multi-ethnic (including non-Hispanic Caucasian, African-American, Hispanic, Japanese-American and Chinese-American) community sample of over 16 000 women aged 40–55 years when screened for the longitudinal cohort, which consisted of over 3300 women aged 42–52 years at baseline (Sowers et al., 2000).

Regression analyses showed significant differences in symptom reporting across the ethnic groups, and differences in reporting on the basis of menopausal status. After controlling for age, education, general health and economic stressors, it was found that Caucasian women reported significantly more symptoms in all, notably psychosomatic symptoms (including ‘tense’, ‘depressed’, ‘irritability’, ‘forgetfulness’ and ‘headaches’), than did the other groups (Avis et al., 2001). However, African-American women reported the most vasomotor symptoms, although their reporting varied considerably by site (Gold et al., 2004). Chinese and Japanese-Americans reported significantly fewer symptoms than did Caucasians, African-Americans, or Hispanics. The researchers conclude that it is not possible to define a single syndrome on the basis of symptomatology associated with declining estrogen levels. Further, they argue that variation in subjective symptom reporting among ethnic groups cannot be set aside as a methodological artefact (Avis et al., 2001).

Two consistent symptom factors emerged from analyses across ethnic groups: vasomotor and psychological/psychosomatic symptoms (Avis et al., 2001). These results are in agreement with earlier studies including the cross-sectional and longitudinal Manitoba and Massachusetts studies which pioneered the use of a general symptom list and factor-analyses of the data (Kaufert et al., 1988; Lock et al., 1988; Avis et al., 1993). Japanese- and Chinese-Americans consistently reported fewer symptoms (including vasomotor) compared to Caucasian women, while African-Americans reported more vasomotor symptoms and vaginal dryness (Gold et al., 2004). Vasomotor and other symptoms were positively associated with BMI, difficulty paying for basic needs and smoking, and negatively associated with physical activity. These results suggest that lifestyle, race/ethnicity and socio-economic status affect symptoms in this age group (Gold et al., 2000). Age at menopause of Japanese-American women was significantly later than that of Hispanic, non-Hispanic White, African-, or Chinese-American women (Gold et al., 2001, 2004).

Relative to non-Hispanic Caucasians, African-American, Japanese-American and Chinese-American women had lower odds of experiencing mood symptoms including feeling blue, nervous or irritable (Bromberger et al., 2003). African-American women had a more positive attitude towards menopause than Hispanic or non-Hispanic White women, and Japanese- and Chinese-Americans expressed the most negative attitudes (Sommer et al., 1999). Compared with non-Hispanic White women, Chinese- and Japanese-American women were less likely to say that sex was very important, whereas African-American women were the most likely to say that sex was important and to report having sexual intercourse more than once a week (Cain et al., 2003).

The SWAN considered various lifestyle factors that may influence the observed differences in symptom reporting. In contrast to studies that have reported low levels of recreational physical activity among African-American and Hispanic women, no significant difference was found between the SWAN ethnic groups in relation to physical activity, but this may be because a global question (comparing an individual's relative physical activity to that of other women their age) was used (Sternfeld et al., 2000). Serum sex steroid, FSH and sex hormone-binding globulin (SHBG) levels varied by ethnicity, but appear to be highly confounded by ethnic disparities in body size (Randolph et al., 2003). Consumption of the soy isoflavone genistein was not associated with vasomotor symptoms in any ethnic group (Gold et al., 2004), but median intake was 4-fold lower (5.4 mg/day, interquartile range 10.1 mg) in these Japanese-Americans than the average intake of 23.2 mg/day among Japanese living in Japan (Kimira et al., 1998). Nevertheless, premenopausal Japanese-Americans with higher genistein intake had higher bone mineral density (Greendale et al., 2002).

The SWAN, with its longitudinal design and relatively large sample sizes, provides important information on ethnic differences in the USA, but some sources of bias should be noted. Recruitment of some ethnic groups proved difficult, resulting in potential biases of subpopulations. Two subpopulations, Japanese-Americans and Chinese-Americans, are likely to be second and third generation, and thus more similar to non-Asian Americans, as evidenced by higher vasomotor symptoms and lower dietary isoflavone intake compared to Japanese living in Japan. (Other ethnic groups, such as Vietnamese, might represent populations of first generation immigrants that should be included in future studies.) Finally, as large numbers of women have quit HRT in the wake of results from the HERSI/II and Women's Health Initiative (Rossouw et al., 1995; Hulley et al., 1998; McDonough, 2002; Randolph, 2002; Rossouw et al., 2002; Manson et al., 2003), another source of bias may be introduced into the results of longitudinal studies carried out in the USA and elsewhere (Nozaki et al., 2004; Paine et al., 2004), as post-menopausal women begin to experience symptoms delayed due to HRT use.

Cross-cultural vasomotor symptom reporting

Anthropological research has consistently shown that the prevalence of vasomotor symptom reporting, notably hot flushes and night sweats, is not distributed equally either between or among populations of peri- and post-menopausal women. Beyene carried out research among rural Mayans living in the Yucatan, Mexico, where women have numerous pregnancies and extended cycles of amenorrhoea associated with prolonged lactation and malnutrition and found no reporting of either hot flushes or cold sweats. In contrast, Greek peasant women, whom she also studied, reported symptoms similar to those commonly reported across northern Europe (Beyene, 1986).

Findings from research carried out in India (Flint, 1975), Indonesia (Flint and Samil, 1990; Boulet et al., 1994), among Africans living in Israel (Walfisch et al., 1994), in Taiwan (Yeh, 1989; Boulet et al., 1994), Hong Kong (Boulet et al., 1994; Haines et al., 1994), Japan (Lock, 1993; Melby, 2005a,b), Singapore (Boulet et al., 1994; McCarthy, 1994), China (Tang, 1994; Shea, 1998), Korea (Boulet et al., 1994), Thailand (Chompootweep et al., 1993; Chirawatkul and Manderson, 1994) and Malaysia (Ismael, 1994), reveal lower reporting of hot flushes and night sweats compared to North American and European populations, although there is considerable variation in prevalence among these studies.

Boulet et al. (1994), on the basis of research in seven South-East Asian countries, showed that headaches, dizziness, anxiety, irritability and other non-specific symptoms were commonly associated by the women in their study with the menopausal transition. Boulet and her associates argue that such symptom reporting should be understood as ‘a form of communication’ on the part of women, and speculate that vasomotor distress may be ‘translated’ by them into culturally meaningful non-specific symptoms that are associated with feelings of psychological distress. The assumption in making such interpretations is that when subjective reporting does not coincide with the findings anticipated by the researchers then women are, in effect, misrepresenting their symptom experience.

In one study in Thailand (Punyahotra et al., 1997), and another in the Philippines (Ramoso-Jalbuena, 1994), prevalence of vasomotor symptom reporting was similar to findings for European countries, and the International Health Foundation study of seven South-East Asian countries found that a little over half of the respondents in Malaysia and Philippines reported hot flushes (Boulet et al., 1994). In Nigeria (Okonofua et al., 1990), Ghana (Kwawukume et al., 1993) and Tanzania (Moore and Kombe, 1991), respectively, 30, 50 and 80% of the women studied reported hot flushes. One third to one half of women surveyed in countries in the Arab world reported them (Rizk et al., 1998; Obermeyer et al., 1999), and in Turkey 74% of surveyed women had experienced such symptoms (Neslihan Carda et al., 1998). A review of literature published in the last 4 years found population rates of hot flushes ranging from 15.1 to 61% (Fuh et al., 2001; Obermeyer et al., 2002); however, comparability is limited by differences in recall periods [2 weeks versus 1 month versus since age 40 (Chim et al., 2002)], symptom inclusiveness [hot flushes only (Lam et al., 2003) or vasomotor symptoms (Joffe et al., 2002)], age range [42–52 years (Gold et al., 2004) to a range from less than 30 to greater than 71 years old (Pan et al., 2002)] and distribution across menopausal status groups (Table III). For example, 24% of Slovenian women experienced a hot flush in the past 2 weeks, but 55% have experienced a hot flush at least once in their lives (Sievert et al., 2004). A population of premenopausal and early perimenopausal Japanese-Americans had a vasomotor symptom rate of 34.4% in the previous 2 weeks (Gold et al., 2004), compared to a 2 week hot flush rate of 22.1% among Japanese living in Japan (the majority of whom were perimenopausal) (Melby, 2005a). Another study of primarily post-menopausal Japanese living in Japan had a symptom rate of 46.6%, but recall period was not reported (Anderson et al., 2004). These examples illustrate the difficulties and limitations of comparing symptom rates and identifying relevant factors without first controlling for methodological differences.

View this table: [in this window] [in a new window]   Table III. Hot flush or vasomotor symptom rates by menopausal status and ethnic group reported in recent studies (2000–2005)

 

An understanding of the cross-cultural differences in symptom reporting requires data on factors influencing the occurrence and experience of hot flushes. A recent review reported that smoking was a consistent risk factor for hot flushes, and factors such as hormone levels, body size, tubal ligation, surgical menopause and race/ethnicity may also be associated with hot flushes (Whiteman et al., 2003). Factors identified as influencing vasomotor symptoms in recent studies (2000–2004) are summarized in Table IV. Some of the factors that have been found to positively associate with reporting of vasomotor symptoms include: age; menopausal status after adjustment for age (with peri- and post- higher than premenopausal; though relative rates of peri- or post-menopausal symptom reporting vary between studies); environmental variables such as ambient temperature and smoking; diet (coffee consumption and egg consumption as a child); FSH; and other comorbidities. Factors with mixed results (positive and negative correlations in different studies) include: BMI and education. Factors that were negatively associated with vasomotor symptoms include: estradiol (E₂); months breastfeeding last child. While these studies have identified factors that may influence vasomotor symptoms, the direction and extent of effect may vary between populations and individuals. Thus systematic data collection on factors influencing vasomotor symptoms is warranted.

View this table: [in this window] [in a new window]   Table IV. Factors influencing vasomotor symptoms identified in recent studies (2000–2004)

 

Much better standardization of research methodologies is called for before firm conclusions can be drawn on the basis of studies such as those cited above. Sample sizes are often small, include widely different age ranges, and several were created out of clinical populations, introducing considerable bias. Sensitivity to the complexity of linguistic expressions (Zeserson, 2001) and translation of bodily terms across languages is often absent. Women who have undergone surgical menopause are not always placed in a separate category for the purposes of analysis. This is problematic because such women often show different symptom reporting (Gold et al., 2000; Keenan et al., 2003). Very often women are asked to recall what may have happened 5 or even 10 years previously. Hot flush frequencies are reported for the previous 2 weeks, 1 month, since menopause or age 40, or ‘ever’, depending on the study. Further bias is introduced if, as is often the case, symptom reporting by women is not stratified by their actual menopausal status (something that is particularly difficult to establish in ethnic groups in which multi-parity is the norm).

Analysis categories and relative proportions of menopausal status subpopulations may also influence the reported symptom prevalence. For example, a recent detailed analysis of a Japanese non-clinical population reported rates of hot flushes of 24.3% for perimenopausal women, but 18.2 and 42.1%, respectively, among early and late perimenopausal women (Melby, 2005a). The latter rate is similar to the hot flush prevalence observed in an Australian population in late perimenopausal and early post-menopausal women of 42% compared with 15% in early perimenopausal women (Dennerstein et al., 2000). Early and late perimenopausal women may differ significantly in their hormone levels (Santoro, 2002), and thus separation of these groups in analyses may be important in identifying women who are most likely to experience vasomotor symptoms. The similarities between the prevalence rates in these two studies are particularly interesting in light of the findings that Australian women were consuming a mean of 17 mg/day (range 0–340 mg) of isoflavones (Guthrie et al., 2000), a level comparable to Japanese intake. Unfortunately, in a recent Japanese-Australian study, although data were collected on early and late perimenopausal status, they are not reported separately (Anderson et al., 2004). Furthermore, while the SWAN study has collected data on these perimenopausal groups (Avis et al., 2001), symptom rates are reported by ethnic group (all menopausal status groups combined) and by menopausal status groups with early and late perimenopause analysed separately (but with all ethnic groups combined) (Gold et al., 2000). Because of the large differences in sample sizes between ethnic groups, this means that the late perimenopausal group consists of approximately 85% African-Americans and non-Hispanic Caucasians, with Japanese, Chinese and Hispanic women comprising the remainder. Although adjusted odds ratios are reported, symptom rates by menopausal status groups, separated by ethnic group, are not, rendering comparisons with other studies' symptom rates difficult.

Due to serious methodological limitations, a meta-analysis of the literature is impossible at this time. Nevertheless, the research to date suggests that there is considerable variation in reporting of vasomotor symptoms across cultures that cannot be explained away as simply due to culturally conditioned inattention or methodological problems. The continuum from relatively high rates of vasomotor symptom reporting in North American Caucasians and African-Americans to low rates in countries like Japan or no reporting of symptoms among rural Mayan women demonstrates that the experience of the perimenopause is not universal.

	Part III: Transition to a biocultural approach

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
The findings cited above in connection with reporting of vasomotor symptoms and age at menopause, when combined with a lifespan approach to the body, suggest that research into menopause should be designed to take biological parameters into consideration including diet and smoking, BMI and reproductive ecological variables such as age at menarche and parity. In addition, psychological variables, including high levels of stress associated with lifestyles, as well as social variables including education, family structure, income and urban or rural residence, should all be included in the analysis. Cultural values associated with ageing and expectations about the menopausal transition should also be taken into consideration; interviews should be conducted in the first language of the informant with an awareness of the specific idioms used in any given language in connection with the end of menstruation and associated symptoms. Furthermore, to what extent menopause is medicalized is crucial to the interpretation of data. It is clear that co-operation across disciplines is required for this type of research.

Biological anthropology and reproductive ecology

Biological anthropology and reproductive ecology have made important contributions to our understanding of human reproductive biology by highlighting the influence of ecological and cultural factors on fertility and chronic disease. In the subsequent discussion of how biology and culture entwine to produce local (individual) experience and knowledge, we use the concept of local biology that highlights the dialectic between, and the interdependence of, culture and biology, and thus the latter's plasticity (Lock, 1993). Marked biological variation among humans in hormonal profiles, reproductive function and symptomatology throughout the reproductive lifespan exists (Panter-Brick et al., 1993; Worthman et al., 1993; Campbell and Wood, 1994; Ellison, 1994; Panter-Brick and Ellison, 1994; Short, 1994; Vitzhum, 1994; Voland, 1998; Wiley, 1998). For example, low luteal phase progesterone levels (Ellison et al., 1993a,b) characterize women in many non-Western ‘natural fertility’ populations, a pattern that has been linked to lower nutrition and increased workload (Ellison et al., 1993a,b; Panter-Brick et al., 1993; Worthman et al., 1993; Panter-Brick and Ellison, 1994; Wood, 1994; Ellison, 1995, 1996; Bentley et al., 1998). Parity, workload and nutritional status may greatly affect ovarian function, and these variables may explain much of the cross-cultural variation as well as exposure to environmental chemicals such as smoking and consumption of soy isoflavones. For example, in the SWAN, serum sex steroids, FSH and SHBG levels varied by ethnicity, but were highly confounded by ethnic differences in BMI (Randolph et al., 2003). Cross-sectional analysis of the SWAN data found that menstrual cycle characteristics varied by age, BMI and ethnicity (Santoro et al., 2004). Another study found that menstrual cycle length varied significantly between Caucasian and Asian women (Liu et al., 2004). Post-industrialized populations in North America and Western Europe (with low parity, relatively sedentary lives and high levels of nutrition) appear to represent an extreme on the continuum of variation in ovarian function, a fact which may relate to the epidemiology of breast and ovarian cancer (Ellison et al., 1993a,b; Eaton et al., 1994), and possibly also the epidemiology of menopausal symptoms.

A higher incidence of reproductive cancers in North American and Western European populations compared to Asian, African or Eastern European populations (Trowell and Burkitt, 1983; Yu et al., 1991) is associated with lower parity, resulting in higher cumulative lifetime exposure to gonadal steroids, particularly estrogens (Henderson et al., 1993; Marshall, 1993; Eaton et al., 1994). This pattern spreads as developing countries adopt Western diet and habits (Adlercreutz, 1990), with modification by use of oral contraceptives. Moreover, although first generation immigrants generally exhibit an incidence rate typical of their country of origin, second generation immigrants often assume the risk of their host country (Shimizu et al., 1991).

Japanese women are of particular interest because their reproductive hormonal profiles and cancer risk resemble women in less developed countries whereas their ecology is more similar to that of the more developed countries (Parkin, 1989; Eaton et al., 1994; Ferlay et al., 2004). They exhibit the low rates of reproductive cancers found in natural fertility populations in spite of the lower parity, later marriage age, higher number of menstrual cycles, higher caloric consumption and decreased workload typical of industrialized nations (JMHLW, 2003a,b). Circulating estrogen levels are low compared to levels in North American women (Goldin et al., 1986; Parkin, 1989; Key et al., 1990; Shimizu et al., 1990), although comparisons of hormone levels between populations often do not control for factors such as smoking, BMI and herbal/dietary exposures. Nevertheless genetic differences are unlikely to be responsible for these differences since the incidence of reproductive cancers approaches U.S. rates when Japanese women emigrate to the U.S. (Shimizu et al., 1991; Maskarinec et al., 2002). Japanese women have low levels of menopausal symptoms (Lock, 1993) as well as breast, ovarian and endometrial cancer (Parkin, 1989) compared to North American women and Japanese living in Hawaii, suggesting that environmental factors rather than solely genetic factors may be involved (Tham et al., 1998). Furthermore, the prevalence of vasomotor symptoms among Japanese-Americans (34.3%) is higher than perimenopausal Japanese living in Japan (13.5%) (Lock, 1993), though still slightly lower than the 36.6% of Caucasian-Americans in the SWAN (Gold et al., 2004). These results suggest that cultural differences may primarily result from local biologies, i.e. biology modified by local cultural and environmental influences.

Cultural influences on local biology: role of diet

The choice of what to eat and how to prepare it is profoundly cultural and is recognized as playing an important role in many aspects of health, from cancer to cardiovascular health and osteoporosis. Lifestyle factors such as exercise and diet (i.e. energy expenditure and caloric intake) are known to influence health and reproductive functioning, but the effects of specific dietary compounds such as phytoestrogens have been largely ignored until recently. Following concerns about the use of HRT at menopause, isoflavones are increasingly being investigated as an alternative to HRT, and despite a lack of conclusive data (Kronenberg and Fugh-Berman, 2002; Valtuena et al., 2003; Huntley and Ernst, 2004), the North American Menopause Society has issued a statement supporting the use of isoflavone supplementation in some cases (NAMS, 2004).

From an epidemiological perspective, populations, such as the Japanese, which consume high amounts of isoflavones in the form of soy, also have documented low levels of reproductive-related cancers and menopausal symptoms. The Japanese diet is unique in including a high proportion of soy, which contains relatively large amounts of the isoflavones daidzein and genistein (Mazur, 1998). Intestinal bacteria convert isoflavones into weakly estrogenic compounds that can influence sex hormone production, metabolism and biological activity, intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, cell adhesion and angiogenesis (Adlercreutz and Mazur, 1997). Recent studies suggest that equol, a metabolite of daidzein, is particularly bioactive, and may account for much of the estrogen-mediated effects of soy and isoflavones (Setchell et al., 2002).

Phytoestrogens are widely believed to exert protective effects on the reproductive system (Punnonen et al., 1987; Horn-Ross, 1995; Murkies et al., 1995; Fujita, 1996; Knight and Eden, 1996; Tanaka et al., 1996; Adlercreutz and Mazur, 1997; Nestel et al., 1997; Baum et al., 1998; Nagata et al., 1998a,b; 1999; Rygwelski and Smith, 1998; Seidl and Stewart, 1998; Tham et al., 1998). Phytoestrogen consumption has been hypothesized to play a role in decreased reproductive-related cancer risk (Horn-Ross, 1995; Yamamoto et al., 2003), cholesterol lipid levels (Baum et al., 1998; Nagata et al., 1998a,b; Zhuo et al., 2004), cardiovascular risk (Nestel et al., 1997), rates of osteoporosis (Cooper et al., 1992; Fujita, 1996; Adlercreutz and Mazur, 1997) and menopausal symptoms such as hot flushes (Nagata et al., 1999, 2001a,b; Washburn et al., 1999; Upmalis et al., 2000; Faure et al., 2002; Kurzer, 2003; Messina and Hughes, 2003) compared to populations who consume relatively few phytoestrogens (Adlercreutz and Mazur, 1997; Murkies et al., 1998; Rygwelski and Smith, 1998; Seidl and Stewart, 1998). Although phytoestrogens are generally weak estrogens, the high plasma concentrations resulting from ingestion of phytoestrogen-rich foods like soy appear to partly compensate for their lower estrogenic potency. In Japan, average dietary intake of isoflavones is approximately 40 mg/day (range 8–88 mg) (Kimira et al., 1998), resulting in plasma concentrations of up to 3 µM, 7.5 times greater than levels in the US vegetarians (0.4 µM) and 42 times greater than levels in the US omnivores (0.07 µM) (Adlercreutz et al., 1991). These levels are up to 50 000 times higher than levels of endogenous E₂. Plasma daidzein concentrations average 30–70 ng/ml and genistein concentrations average 75–105 ng/ml in Japanese women (Adlercreutz et al., 1993, 1994). However, the timing of exposure (i.e. before puberty) appears critical for protective effects on breast cancer (Limer and Speirs, 2004), and may be important for influencing menopausal symptoms as well.

Clinical studies of North American and European women have produced mixed results, but are consistent with the notion that the pattern of phytoestrogen actions may vary with endogenous estrogen levels. In premenopausal women, a soy supplement of 0.8 mg/kg increased E₂ early in the follicular phase and reduced midcycle LH and FSH (Cassidy et al., 1994), while a 3 mg/kg supplement reduced E₂ on days 11 and 22 of the cycle (Lu et al., 1996). In post-menopausal American women, soy phytoestrogens have been found to decrease LH secretion (Van Thiel et al., 1991) and hot flushes (Murkies et al., 1995; Albertazzi et al., 1998; Whitten and Naftolin, 1998), but not all studies have been able to demonstrate a difference from the normal decline in symptoms over time (Murkies et al., 1995; Brzezinski and Debi, 1999) or placebo (Burke et al., 2003; Tice et al., 2003). Overall, randomized controlled studies on the effects of isoflavones on menopausal symptoms have been inconclusive due to limitations of small sample sizes and short-term treatment. Observational studies of Japanese women, which have produced more consistently positive results (Nagata et al., 2001a,b), have been larger in size and have focused on women consuming soy over long periods of time, although self-selective factors may affect intake and outcomes. Effects in populations with habitual dietary soy intake (Ho et al., 2003) may differ from those populations in the West where extracted isoflavones are ingested over a limited time period. In post-menopausal Japanese women (Nagata et al., 1999) and in a community-based prospective study (Nagata et al., 2001a,b), hot flushes were inversely associated with soy and isoflavone intake.

Disparities between epidemiological data and clinical data may result in part from the following: small sample sizes and large placebo effect in many clinical studies; developmental influences of chronic soy consumption versus short-term interventions; other components of soy foods that are beneficial such as peptides (Kurzer, 2003); populational differences in gut microflora and equol-producing ability; and isoflavone source. In most intervention studies, equol-producing ability is not assessed, and subpopulations are not separated for analyses. Recent data suggest that only individuals capable of metabolizing the isoflavone daidzein into equol may receive significant health benefits, and thus populations must be analysed separately by microflora and metabolic characteristics (Setchell et al., 2002). Significant results are likely to be obscured when subpopulations are analysed together, particularly in those studies carried out among Western populations in which only approximately 30% are equol producers (Setchell et al., 2003) compared to Japanese populations where 50–60% of menopausal women are equol producers (S. Watanabe, personal communication, 2004). Furthermore, many menopausal intervention studies use isoflavones derived from clover (as opposed to soy), which has a much lower ratio of daidzein to genistein than soy germ, and thus results in lower levels of equol in equol producers (Watanabe et al., 2005).

	Part IV: Exemplary case studies of biocultural studies of menopause

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
The results of several recent studies support the need for a move to interdisciplinary research. In this section we review: (1) one of the first biocultural studies of menopause, conducted among Mayan women in Mexico; (2) a recent cross-cultural study between Japan and Australia; (3) a cross-cultural study between Japan and North America utilizing similar, comparable methodology with recent data from Japan for a longitudinal comparison.

Menopause among Maya in Yucatan, Mexico

In a project carried out by a multidisciplinary team that followed up on the earlier study by Beyene (1989), in a sample of over 228 Mayan women whose average age at menopause was 44.3 (range 18–80 years, 118 post-menopausal women), endocrine changes at menopause were very similar to those of North American women. As in the earlier study, no hot flushes were reported (except very occasionally after migration to an urban environment) (Martin et al., 1993; Beyene and Martin, 2001). Plasma, urinary and vaginal levels of estrogens neither relate neatly with subjective reporting of hot flushes (Freedman, 2001) nor do measured rates of sternal skin conductance, sweating, peripheral vasodilation, or deregulation of core body temperature (Freedman, 2001; Sievert et al., 2002). Clearly considerable mediation takes place between measurable physiological changes, subjective experience and the reporting of symptoms, some of which may be accounted for by as yet poorly understood biological pathways (Kronenberg, 1990; Ginsburg and Hardiman, 1994). It is reasonable to speculate, for example, that with urban migration and education women might experience hot flushes more frequently as a result of dietary changes or due to a more sedentary lifestyle. In addition, cultural expectations, local values and language may also be implicated, although it would be entirely inappropriate to reduce reporting of debilitating hot flushes entirely to changes in attitudes and education.

While self-report of hot flushes may be influenced by language and culture, osteoporosis can be objectively assessed by measurement of bone mineral density. Among Mayan women, bone mineral density declines with age to values that are on average lower than those for American women, but no fractures were detected even though some (n=32) were 20 years post-menopausal (Beyene and Martin, 2001). Thus some combination of environment, diet and lifestyle must be contributory.

Martin et al. (1993) documented a population of post-menopausal Mayan women who, despite having similar endocrinology to North American populations and experiencing age-related bone demineralization, did not report hot flushes and did not have a high incidence of osteoporotic fractures. In contrast, Sievert et al. (2002) found that a number of urban Mexican women reported and demonstrated hot flushes (by sternal skin conductance) (though some reported but did not have measurable hot flushes and vice versa).

Australian and Japanese Midlife Women's Health Study

The relationships among menopausal status, country of residence and symptoms were examined in 886 Australian and 848 Japanese women (aged 40–60 years) (Anderson et al., 2004). Surveys including data on menopausal symptoms (using the Greene Climacteric Scale), menstrual history and sociodemographics were mailed to randomly selected populations in both countries with response rates of 58 and 56% in Australia and Japan, respectively. More than half of the women were post-menopausal, 14.5% were perimenopausal and 12.3% were premenopausal. In both cultures similar increases in prevalence of depression, somatic symptoms and vasomotor symptoms were observed in the perimenopause. Statistically significant differences were observed in psychological symptoms, somatic symptoms and sexual symptoms by menopausal status but not by country of residence. Statistically significant differences in vasomotor symptoms were observed by menopausal status and country of residence. Australian women experienced more night sweats than Japanese women, but the prevalence of hot flushes was not statistically different. Vasomotor, psychological and somatic symptoms decreased after menopause in Australian women, with only sexual symptoms continuing. In Japanese women, somatic, psychological and sexual symptoms remained high after menopause. Rates of symptom reporting in this study were higher than those found in other studies of Japanese general populations (Lock, 1993; Melby, 2005a), and may be due to historical changes, geographical differences, differences in recall period (i.e. 2 week recall period in Lock and Melby and unspecified period in the above study), inclusion of cases of surgical menopause in symptom rate data, participation bias due to low participation rates (i.e. participation rates could have been higher among symptomatic women, resulting in a study population with higher symptom rates) and differences in the ways symptom terms were translated [i.e. the Australian and Japanese Midlife Women's Health Study (AJMWHS) reduced cultural bias by making the English and Japanese surveys consistent, but as several researchers have noted, Japanese hot flush terminology is more detailed and not easily translated into English (Lock, 1993; Zeserson, 2001; Melby, 2005a)].

An earlier paper by the same authors compared symptoms among 712 Australian and 1502 Japanese women aged 46–60 years old. Reported hot flush rates did not differ siginificantly between the two countries nor between menopausal status groups in either country (Anderson et al., 2004). The latter result is particularly surprising, as almost all studies have found significantly higher rates in peri- and post-menopausal women compared to premenopausal women. However, this study used different menopausal symptom scales, generated separately in each country, and thus the findings are potentially not comparable, highlighting a major difficulty in carrying out cross-cultural research.

Longitudinal findings from Japan and comparisons with North America

One of the first examples of interdisciplinary, cross-cultural research to demonstrate variation in symptom reporting was completed in the 1980s. Analysis of data sets designed to be statistically comparable, comprised of 7802 Massachusetts women (Avis and McKinlay, 1991), 1307 Manitoban women (Kaufert, 1984) and 1225 Japanese women (Lock, 1993), all aged between 45 and 55 inclusively, revealed differences in symptom reporting at menopause. In all three sites, samples were selected from a general and not a clinical population of women. Those women who had undergone gynaecological surgery were treated as a separate category in the analyses.

The Japanese word kônenki, usually translated into English as menopause, does not convey the same meaning as does menopause, rather it is similar to the concept of the climacteric, that is, it is understood as a long, gradual process to which the end of menstruation is just one contributing factor. Most Japanese respondents in the study placed its timing at aged 45 or even earlier, lasting until nearly 60. One quarter of the questionnaire respondents who were post-menopausal and had ceased menstruation for over 1 year reported that they had no sign of kônenki. This suggests strongly that it is important, before creating questionnaires, to establish just what is conveyed by local terminology. A second difficulty arose in the research in Japan because, as is the case in many other societies, no word exists in Japanese that refers uniquely and specifically to the menopausal hot flush, even though Japanese is a language in which very fine discriminations can be made in connection with bodily states. In fact several words are used to denote a hot flush depending on the location and attributes of the symptom, but these words can also be used to refer to feelings of heat resulting from non-menopausal causes such as cold/flu, soaking in the bath and after effects of drinking too much alcohol (Zeserson, 2001; Melby, 2005a,b).

In the comparative study women were asked to recall symptoms that they had experienced over the previous 2 weeks. The rates of multiple symptoms reporting by Japanese women were consistently lower than for North American women. No association was evident between menopausal status and general symptom reporting among the Japanese respondents, although among both Canadian and US women symptom reporting was increased during the peri and early post-menopause. Japanese reporting of hot flushes in the previous 2 weeks was low, 13.5 and 15.2% for peri and post-menopausal women, respectively, but were associated with menopausal status. Reporting of night sweats was extremely low and not associated with menopausal status. Only 19% of Japanese women in this study had experienced a hot flush at some time in the past, and both reporting of frequency and intensity was much lower than among USA and Canadian respondents. Reporting of sleep disturbance by Japanese women, at 11.5%, was low, corroborating their reports about lack of severity of hot flushes.

Japanese reporting in connection with feeling ‘blue’ or depressed is low and not associated with menopausal status, since it is highest among premenopausal women. Canadian reporting, although higher than the Japanese, also showed little change across menopausal status. These different patterns of reporting argue strongly against any simple causal link between declining endogenous estrogen levels and reporting of depression.

It is well known that Japanese women currently enjoy the longest life expectancy in the world—a mean of 85.33 years in 2003 (JMHLW, 2003a,b). The incidence of breast cancer (age-standardized world rates) is about one third of that in North America (Ferlay et al., 2004), and the incidence of osteoporosis for Japanese women is less than half that of Caucasian women in North America, even though Asian women on the whole have a lower bone density (Ross et al., 1991). The present research also showed that only 28% of Japanese respondents suffer from a chronic health problem (diabetes, allergies, asthma, arthritis, high blood pressure), as opposed to 45% of Manitoban women and 53% of Massachusetts women. Taken together these figures suggest that middle-aged Japanese women enjoy somewhat better health than do those in North America.

Japanese women who were around 50 years of age when this study was done were born at the beginning of the Second World War, and many experienced nutritional deprivation as very small children. However, virtually none of them have smoked; alcohol and coffee consumption is low, and the diet is low in fat and rich in soybeans and vegetables. Soybeans are a source of phytoestrogens and may well contribute at least in part to the lower symptom reporting of hot flushes among Japanese women (Lock, 1993). So too may the herbal teas that many women drink, some of them also rich in phytoestrogens. This cohort of women have, as part of their daily lives, always done considerable exercise and weight bearing. Given dietary changes in Japan, this picture is very likely to change as succeeding generations of Japanese women in their turn become middle aged.

Twenty years later, results from field research in 2001–2003 (Melby, 2005a) suggest the 2 week prevalence rates of hot flushes have more than doubled compared to the rates reported by Lock, perhaps in part due to lifestyle changes such as westernization of diet and/or medicalization of kônenki; however, the prevalence remains lower than that of Japanese- (and Caucasian-) American women (Gold et al., 2004). In this recent study 140 women aged 45–55 years old inclusively were selected from a general population of women who had not undergone gynaecological surgery or used hormones. The prevalence of any type of hot flush was 22.1% (24.3% for perimenopausal women, but 42.1% for late and only 18.2% for early perimenopausal women) and night sweats and sudden sweating were reported by only 6.4 and 8.6% of the participants, respectively (Melby, 2005a). Furthermore, in a factor analysis of symptoms, night sweats were not associated with hot flushes (Melby, 2005b).

In the intervening years between Lock's and Melby's research in Japan, considerable medicalization of menopause has occurred (Kaufert and Lock, 1997). Kônenki has been given extensive coverage in the popular press (Zeserson, 2001) to the extent that most people (even men and younger women) now discuss the difficult time at kônenki, understand that hormones are involved, and associate hot flushes as well as irritability with this period of life. The westernization and medicalization of menopause is embodied in the language in the terms hotto furasshu and horumon baransu (hormone balance) that often appear in the media (Zeserson, 2001). Given the increased attention to kônenki, it is not surprising that reporting of vasomotor symptoms has increased among Japanese women. However, it is significant that despite the medicalization and media attention, rates of vasomotor symptoms among Japanese women continue to be considerably lower than among Caucasian and Japanese Americans (Gold et al., 2004). The medicalization of kônenki parallels the westernization of the diet as well as lifestyle changes that are reflected in the increase of obesity, diabetes, cancer and cardiovascular disease (Kato et al., 1987; Kodama et al., 1991; Tominaga and Kuroishi, 1997; Yamada et al., 1997).

Kônenki is often characterized as a time when the body ‘loses its balance’ (Lock, 1993), and is attributed by Japanese to both cultural and biological causes. With medicalization, Japanese women now talk about ‘hormone balance’, but notably they rarely mention ‘estrogen depletion’ as is sometimes discussed in the North America. Given the problematic assumptions about the benefits of estrogen replacement therapy, the Japanese focus on ‘hormone balance’ may prove to be a more biologically accurate view.

An argument can be made that the healthy longevity of Japanese women be attributed in large part to the relatively even distribution of wealth in Japanese society and equal access to good health care and social benefits, added to which is universal public education of a high quality, and a long tradition of both public and familial investment in preventive medicine. These conditions are without doubt much more important in contributing to the good health of middle-aged Japanese women than are any shared cultural beliefs that they have. In addition, it seems highly likely that the Japanese diet—low in fat, high in protein and plant estrogens—plays an important role in low symptom reporting at the end of menstruation, and in longevity. Genetics may, of course, also make a contribution.

Some additional findings of interest come from the research of Jean Shea with 400 Chinese women. Shea used methods readily comparable with those used in the comparative project reported above. Vasomotor symptom reporting among the Chinese women in this study is low and resembles that of the Japanese sample discussed above. However, the overall symptom reporting of the Chinese women is considerably higher than the Massachusetts, Manitoba and Japanese samples, leading Shea to conclude that sweeping generalizations about East Asia should be avoided (Shea, 1998).

	Conclusions

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
Research into culture and menopause has undergone several transitions over the years. In the first phase, cultural differences in symptom reporting and the subjective experience of menopause were noted. Research then proliferated to document first, if these differences were ‘real’, and second how culturally related factors might account for them. In the bulk of this research, culture is conceived as layered over an invariant biological base. More recently, research such as the SWAN and that carried out in Asia and elsewhere has made it clear that even when the contribution of culture to menopause is investigated with care a great deal of variation is left unaccounted for.

In virtually all research paradigms, menopause has been detached from the rest of life, particularly what precedes it. Most research on menopause begins at the earliest in the late premenopause, and often ignores reproductive and dietary history that may be expressed/manifested in the menopausal body. Models need to be developed of the interaction between biological and cultural factors across the lifespan that influence the menopausal experience. Clearly more interdisciplinary, methodologically-rigorous research is required before comparative meta-analyses can be done. Elucidation of systematic patterns is crucial but so too is attention to specific contexts. Further, cohort effects need careful scrutiny, such as the menopausal women studied by Lock who were born during world war II, compared to those currently being studied by Melby who have experienced a greater degree of westernization of diet and medicalization of menopause.

Obermeyer has argued that we need longitudinally designed studies using standardized questionnaires and an agreed-upon definition of menopause in order to carry out good cross cultural work (Obermeyer et al., 1999). However, it is important to acknowledge that, when researching symptom reporting an agreed upon definition of menopause would essentially be something that is imposed on women everywhere in order to achieve apparent objectivity. In reality, many problems would result with data interpretation, as has already repeatedly been the case, and many findings of variation are ruled out as inauthentic because they are assumed to be culturally produced. There is no universal menopausal entity or experience waiting to be exposed through systematic inquiry (although the end of menstruation is, of course, universal). Systematization and rigorous analyses are needed, but these will lead us, not to the essence of menopause, but to what is relevant for comparative purposes.

	Acknowledgements

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 
This research was partially funded by the Social Science and Humanities Research Council of Canada grant # 410 93 0544 (ML) and by the USA National Institute of Health (NIH) National Center for Complementary and Alternative Medicine (NCCAM) National Research Service Award (NRSA) #1 F31 AT01041-01 (MKM). Julia Freeman's meticulous work to locate and obtain copies of the papers reviewed, and Jan Zeserson's close reading of the manuscript and helpful comments are gratefully acknowledged.

	References

TOP Abstract Introduction Part I: Factors contributing... Part II: Review of... Part III: Transition to... Part IV: Exemplary case... Conclusions References

 

Adamopoulos DA, Karamertzanis M, Thomopoulos A, Pappa A, Koukkou E and Nicopoulou SC (2002) Age at menopause and prevalence of its different types in contemporary Greek women. Menopause 9, 443–448.[CrossRef][Web of Science][Medline]

Adler SR, Fosket JR, Kagawa-Singer M, McGraw SA, Wong-Kim E, Gold E and Sternfeld B (2000) Conceptualizing menopause and midlife: Chinese American and Chinese women in the US. Maturitas 35, 11–23.[CrossRef][Web of Science][Medline]

Adlercreutz H (1990) Western diet and Western diseases: some hormonal and biochemical mechanisms and associations. Scand J Clin Lab Invest Suppl 201, 3–23.

Adlercreutz H and Mazur W (1997) Phyto-oestrogens and Western diseases. Ann Med 29, 95–120.[Web of Science][Medline]

Adlercreutz H, Honjo H, Higashi A, Fotsis T, Hämäläinen E, Hasegawa T and Okada H (1991) Urinary excretion of lignans and isoflavonoid phytoestrogens in Japanese men and women consuming a traditional Japanese diet. Am J Clin Nutr 54, 1093–1100.[Abstract/Free Full Text]

Adlercreutz H, Markkanen H and Watanabe S (1993) Plasma concentrations of phyto-oestrogens in Japanese men. Lancet 342, 1209–1210.[CrossRef][Web of Science][Medline]

Adlercreutz H, Fotsis T, Watanabe S, Lampe J, Wahala K, Makela T and Hase T (1994) Determination of lignans and isoflavonoids in plasma by isotope dilution gas chromatography-mass spectrometry. Cancer Detect Prev 18, 259–271.[Web of Science][Medline]

Albertazzi P, Pansini F, Bonaccorsi G, Zanotti L, Forini E and De Aloysio D (1998) The effect of dietary soy supplementation on hot flushes. Obstet Gynecol 91, 6–11.[CrossRef][Web of Science][Medline]

Alderson P, Green S and Higgins J (eds) (2004) Section 4. Assessment of study quality. In Cochrane Reviewers' Handbook 4.2.2.

Anderson D, Yoshizawa T, Gollschewski S, Atogami F and Courtney M (2004) Menopause in Australia and Japan: effects of country of residence on menopausal status and menopausal symptoms. Climacteric 7, 165–174.[CrossRef][Web of Science][Medline]

Avis NE and McKinlay SM (1991) A longitudinal analysis of women's attitudes toward the menopause: results from the Massachusetts Women's Health Study. Maturitas 13, 65–79.[CrossRef][Web of Science][Medline]

Avis NE, Kaufert PA, Lock M, McKinlay SM and Vass K (1993) The evolution of menopausal symptoms. Baillieres Clin Endocrinol Metab 7, 17–32.[CrossRef][Web of Science][Medline]

Avis NE, Crawford SL and McKinlay SM (1997) Psychosocial, behavioral, and health factors related to menopause symptomatology. Womens Health 3, 103–120.[Medline]

Avis NE, Stellato R, Crawford S, Bromberger J, Ganz P, Cain V and Kagawa-Singer M (2001) Is there a menopausal syndrome? Menopausal status and symptoms across racial/ethnic groups. Soc Sci Med 52, 345–356.[CrossRef][Web of Science][Medline]

Avis NE, Ory M, Matthews KA, Schocken M, Bromberger J and Colvin A (2003) Health-related quality of life in a multiethnic sample of middle-aged women: Study of Women's Health Across the Nation (SWAN). Med Care 41, 1262–1276.[CrossRef][Web of Science][Medline]

Avis NE, Assmann SF, Kravitz HM, Ganz PA and Ory M (2004) Quality of life in diverse groups of midlife women: assessing the influence of menopause, health status and psychosocial and demographic factors. Qual Life Res 13, 933–946.[CrossRef][Web of Science][Medline]

Baum JA, Teng H, Erdman JW, Jr, Weigel RM, Klein BP, Persky VW, Freels S, Surya P, Bakhit RM, Ramos E et al. (1998) Long-term intake of soy protein improves blood lipid profiles and increases mononuclear cell low-density-lipoprotein receptor messenger RNA in hypercholesterolemic, postmenopausal women. Am J Clin Nutr 68, 545–551.[Abstract]

Bell SE (1987) Changing ideas: the medicalization of menopause. Soc Sci Med 24, 535–542.[CrossRef][Web of Science][Medline]

Bentley GR, Harrigan AM and Ellison PT (1998) Dietary composition and ovarian function among Lese horticulturalist women of the Ituri Forest, Democratic Republic of Congo. Eur J Clin Nutr 52, 261–270.[CrossRef][Web of Science][Medline]

Berg JA and Taylor DL (1999) Symptom responses of midlife Filipina Americans. Menopause 6, 115–121.[Web of Science][Medline]

Beyene Y (1986) Cultural significance and physiological manifestations of menopause: a biocultural analysis. Cult Med Psychiatry 10, 47–71.[CrossRef][Web of Science][Medline]

Beyene Y (1989) From Menarche to Menopause: Reproductive Lives of Peasant Women in Two Cultures. State University of New York Press, Albany, New York.

Beyene Y and Martin MC (2001) Menopausal experiences and bone density of Mayan women in Yucatan, Mexico. Am J Hum Biol 13, 505–511.[CrossRef][Web of Science][Medline]

Biri A, Bakar C, Maral M, Karabacak O and Bumin MA (2005) Women with and without menopause over age of 40 in Turkey: consequences and treatment options. Maturitas 50, 167–176.[CrossRef][Web of Science][Medline]

Boulet MJ, Oddens BJ, Lehert P, Vemer HM and Visser A (1994) Climacteric and menopause in seven South-east Asian countries. Maturitas 19, 157–176.[CrossRef][Web of Science][Medline]

Bromberger JT, Assmann SF, Avis NE, Schocken M, Kravitz HM and Cordal A (2003) Persistent mood symptoms in a multiethnic community cohort of pre- and perimenopausal women. Am J Epidemiol 158, 347–356.[Abstract/Free Full Text]

Bromberger JT, Matthews KA, Kuller LH, Wing RR, Meilahn EN and Plantinga P (1997) Prospective study of the determinants of age at menopause. Am J Epidemiol 145, 124–133.[Abstract/Free Full Text]

Bromberger JT, Meyer PM, Kravitz HM, Sommer B, Cordal A, Powell L, Ganz PA and Sutton-Tyrrell K (2001) Psychologic distress and natural menopause: a multiethnic community study. Am J Public Health 91, 1435–1442.[Abstract/Free Full Text]

Brzezinski A and Debi A (1999) Phytoestrogens: the "natural" selective estrogen receptor modulators? Eur J Obstet Gynecol Reprod Biol 85, 47–51.[CrossRef][Web of Science][Medline]

Burke GL, Legault C, Anthony M, Bland DR, Morgan TM, Naughton MJ, Leggett K, Washburn SA and Vitolins MZ (2003) Soy protein and isoflavone effects on vasomotor symptoms in peri- and postmenopausal women: the Soy Estrogen Alternative Study. Menopause 10, 147–153.[CrossRef][Web of Science][Medline]

Cain VS, Johannes CB, Avis NE, Mohr B, Schocken M, Skurnick J and Ory M (2003) Sexual functioning and practices in a multi-ethnic study of midlife women: baseline results from SWAN. J Sex Res 40, 266–276.[Web of Science][Medline]

Campbell K and Wood J (1994) Human reproductive ecology: Interactions of environment, fertility, and behavior. Ann NY Acad Sci.

Cassidy A, Bingham S and Setchell KD (1994) Biological effects of a diet of soy protein rich in isoflavones on the menstrual cycle of premenopausal women. Am J Clin Nutr 60, 333–340.[Abstract/Free Full Text]

Chim H, Tan BH, Ang CC, Chew EM, Chong YS and Saw SM (2002) The prevalence of menopausal symptoms in a community in Singapore. Maturitas 41, 275–282.[CrossRef][Web of Science][Medline]

Chirawatkul S and Manderson L (1994) Perceptions of menopause in northeast Thailand: contested meaning and practice. Soc Sci Med 39, 1545–1554.[CrossRef][Web of Science][Medline]

Chompootweep S, Tankeyoon M, Yamarat K, Poomsuwan P and Dusitsin N (1993) The menopausal age and climacteric complaints in Thai women in Bangkok. Maturitas 17, 63–71.[CrossRef][Web of Science][Medline]

Collins A (2002) Sociocultural Issues in Menopause. International Position on Women's Health and Menopause: A Comprehensive Approach. (NIH) NIoH, U.S. Dept. of Health & Human Services,pp 65–76.

Collins A and Landgren BM (1995) Reproductive health, use of estrogen and experience of symptoms in perimenopausal women: a population-based study. Maturitas 20, 101–111.[CrossRef]

Cooper C, Champion G and Melton L (1992) Hip fracture in the elderly: a world wide projection. Osteoporos Int 2, 825–829.

Davis DL (1997) Blood and nerves revisited: menopause and the privatization of the body in a Newfoundland postindustrial fishery. Med Anthropol Q 11, 3–20. Discussion 21–25.[CrossRef][Web of Science][Medline]

Dennerstein L, Smith AM, Morse C, Burger H, Green A, Hopper J and Ryan M (1993) Menopausal symptoms in Australian women. Med J Aust 159, 232–236.[Web of Science][Medline]

Dennerstein L, Dudley EC, Hopper JL, Guthrie JR and Burger HG (2000) A prospective population-based study of menopausal symptoms. Obstet Gynecol 96, 351–358.[CrossRef][Web of Science][Medline]

Dennerstein L, Guthrie J, Birkhauser M and Sherman S (2002) Symptoms and the Menopause. In International Position on Women's Health and Menopause: A Comprehensive Approach. (NIH) NIoH, U.S. Dept. of Health & Human Services,pp 65–76.

Du Toit BM (1990) Aging and Menopause among Indian South African Women. State University of New York Press, Albany.

Eaton SB, Pike MC, Short RV, Lee NC, Trussel J, Hatcher RA, Wood JW, Worthman CM, Jones NGB, Konner MJ et al. (1994) Women's reproductive cancers in evolutionary context. Q Rev Biol 69, 353–367.[CrossRef][Medline]

Ellison P (1994) Advances in human reproductive ecology. Annu Rev Anthropol 23, 255–275.[CrossRef][Web of Science][Medline]

Ellison PT (1995) Understanding natural variation in human ovarian function. In Dunbar RIM (ed) Human Reproductive Decisions. St. Martin's Press, New York, pp 22–51.

Ellison PT (1996) Developmental influences on adult ovarian function. Am J Hum Biol, 8.

Ellison PT, Lipson SF, O'Rourke MT, Bentley GR, Harrigan AM, Panter-Brick C and Vizthum VJ (1993a) Population variation in ovarian function [letter]. Lancet 342, 433–434.[CrossRef][Web of Science][Medline]

Ellison PT, Panter-Brick C, Lipson SF and O'Rourke MT (1993b) The ecological context of human ovarian function. Hum Reprod 8, 2248–2258.[Abstract/Free Full Text]

Estok PJ and O'Toole R (1991) The meanings of menopause. Health Care Women Int 12, 27–39.[Medline]

Faure ED, Chantre P and Mares P (2002) Effects of a standardized soy extract on hot flushes: a multicenter, double-blind, randomized, placebo-controlled study. Menopause 9, 329–334.[CrossRef][Web of Science][Medline]

Ferlay J, Bray F, Pisani P and Parkin DM (2004) GLOBOCAN 2002: Cancer Incidence, Mortality and Prevalence Worldwide. IARC Press, Lyon.

Flint M (1975) The menopause: reward or punishment? Psychosomatics 16, 161–163.[Free Full Text]

Flint M and Samil RS (1990) Cultural and subcultural meanings of the menopause. Ann NY Acad Sci 592, 134–148.[Web of Science][Medline]

Freedman RR (2001) Physiology of hot flashes. Am J Hum Biol 13, 453–464.[CrossRef][Web of Science][Medline]

Fuh JL, Wang SJ, Lu SR, Juang KD and Chiu LM (2001) The Kinmen women-health investigation (KIWI): a menopausal study of a population aged 40–54. Maturitas 39, 117–124.[CrossRef][Web of Science][Medline]

Fujita T (1996) Clinical guidelines for the treatment of osteoporosis in Japan. Calcif Tissue Int 59, 34–37.[Medline]

Fujita M, Yano T, Ohno Y, Sasai Y, Miura S and Tsuji S (2000) The prevalence and the characteristics of shoulder stiffness and its relationship with mental stress and the general states evaluated according to the theory of Oriental medicine among high school students. Health Sci 16, 223–235.

Gannon L (1985) Menstrual Disorders and Menopause: Biological, Psychological, and Cultural Research. Praeger, New York.

Ginsburg J and Hardiman P (1994) The menopausal hot flush: facts and fancies. In Berg G and Hammer M (eds) The Modern Management of the Menopause. Parthenon Publishing Group, New York, pp 123–135.

Gold EB (2000) Demographics, environmental influences, and ethnic and international differences in the menopausal experience. In Lobo R, Marcus R, and Kelsey J (eds) Menopause: Biology and Pathobiology. Academic Press, San Diego, pp 189–201.

Gold EB, Sternfeld B, Kelsey JL, Brown C, Mouton C, Reame N, Salamone L and Stellato R (2000) Relation of demographic and lifestyle factors to symptoms in a multi-racial/ethnic population of women 40–55 years of age. Am J Epidemiol 152, 463–473.[Abstract/Free Full Text]

Gold EB, Bromberger J, Crawford S, Samuels S, Greendale GA, Harlow SD and Skurnick J (2001) Factors associated with age at natural menopause in a multiethnic sample of midlife women. Am J Epidemiol 153, 865–874.[Abstract/Free Full Text]

Gold EB, Block G, Crawford S, Lachance L, FitzGerald G, Miracle H and Sherman S (2004) Lifestyle and demographic factors in relation to vasomotor symptoms: baseline results from the study of women's health across the nation. Am J Epidemiol 159, 1189–1199.[Abstract/Free Full Text]

Goldin BR, Adlercreutz H, Gorbach SL, Woods MN, Dwyer JT, Conlon T, Bohn E and Gershoff SN (1986) The relationship between estrogen levels and diets of Caucasian American and Oriental immigrant women. Am J Clin Nutr 44, 945–953.[Abstract/Free Full Text]

Greendale GA, FitzGerald G, Huang MH, Sternfeld B, Gold E, Seeman T, Sherman S and Sowers M (2002) Dietary soy isoflavones and bone mineral density: results from the study of women's health across the nation. Am J Epidemiol 155, 746–754.[Abstract/Free Full Text]

Greene JG (1998) Constructing a standard climacteric scale. Maturitas 29, 25–31.[CrossRef][Web of Science][Medline]

Guthrie JR, Ball M, Murkies A and Dennerstein L (2000) Dietary phytoestrogen intake in mid-life Australian-born women: relationship to health variables. Climacteric 3, 254–261.[CrossRef][Medline]

Haines CJ, Chung TK and Leung DH (1994) A prospective study of the frequency of acute menopausal symptoms in Hong Kong Chinese women. Maturitas 18, 175–181.[CrossRef][Web of Science][Medline]

Henderson BE, Ross RK and Pike MC (1993) Hormonal chemoprevention of cancer in women. Science 259, 633–638.[Abstract/Free Full Text]

Ho SC, Woo J, Lam S, Chen Y, Sham A and Lau J (2003) Soy protein consumption and bone mass in early postmenopausal Chinese women. Osteoporos Int 14, 835–842.[CrossRef][Web of Science][Medline]

Horn-Ross PL (1995) Phytoestrogens, body composition, and breast cancer. Cancer Causes Control 6, 567–573.[CrossRef][Web of Science][Medline]

Hulley S, Grady D, Bush T, Furberg C, Herrington D, Riggs B and Vittinghoff E (1998) Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and Estrogen/progestin Replacement Study (HERS) Research Group. J Am Med Assoc 280, 605–613.[Abstract/Free Full Text]

Huntley AL and Ernst E (2004) Soy for the treatment of perimenopausal symptoms—a systematic review. Maturitas 47, 1–9.[CrossRef][Web of Science][Medline]

Hvas L (2001) Positive aspects of menopause: a qualitative study. Maturitas 39, 11–17.[CrossRef][Web of Science][Medline]

Hvas L, Thorsen H and Sondergaard K (2003) Discussing menopause in general practice. Maturitas 46, 139–146.[CrossRef][Web of Science][Medline]

Ismael NN (1994) A study on the menopause in Malaysia. Maturitas 19, 205–209.[CrossRef][Web of Science][Medline]

Jacobsen BK, Heuch I and Kvale G (2003) Age at natural menopause and all-cause mortality: a 37-year follow-up of 19,731 Norwegian women. Am J Epidemiol 157, 923–929.[Abstract/Free Full Text]

JMHLW Japanese Ministry of Health, Labour and Welfare (2003a) Abridged Life Tables for Japan 2003. http://www.mhlw.go.jp/english/database/db-hw/lifetb03/1.html.

JMHLW Japanese Ministry of Health, Labour and Welfare (2003b) Summary of Vital Statistics. http://www.mhlw.go.jp/english/database/db-hw/populate/pop4.html.

Joffe H, Hall JE, Soares CN, Hennen J, Reilly CJ, Carlson K and Cohen LS (2002) Vasomotor symptoms are associated with depression in perimenopausal women seeking primary care. Menopause 9, 392–398.[CrossRef][Web of Science][Medline]

Kato I, Tominaga S and Kuroishi T (1987) Relationship between westernization of dietary habits and mortality from breast and ovarian cancers in Japan. Jpn J Cancer Res 78, 349–357.[Web of Science]

Kaufert P (1984) Research note—women and their health in the middle years: a Manitoba project. Soc Sci Med 18, 279–281.[CrossRef][Web of Science][Medline]

Kaufert PL (1990) Methodological issues in menopause research. Ann NY Acad Sci, 114–122.

Kaufert PA and Gilbert P (1986) Women, menopause, and medicalization. Cult Med Psychiatry 10, 7–21.[CrossRef][Web of Science][Medline]

Kaufert PA and Lock M (1997) Medicalization of women's third age. J Psychosom Obstet Gynaecol 18, 81–86.[Medline]

Kaufert P, Boggs PP, Ettinger B, Woods NF and Utian WH (1998a) Women and menopause: beliefs, attitudes, and behaviors. The North American Menopause Society 1997 Menopause Survey. Menopause 5, 197–202.[Web of Science][Medline]

Kaufert PA, Gilbert P and Hassard T (1988b) Researching the symptoms of menopause: an exercise in methodology. Maturitas 10, 117–131.[CrossRef][Web of Science][Medline]

Keenan NL, Mark S, Fugh-Berman A, Browne D, Kaczmarczyk J and Hunter C (2003) Severity of menopausal symptoms and use of both conventional and complementary/alternative therapies. Menopause 10, 507–515.[CrossRef][Web of Science][Medline]

Kesslak JP (2002) Can estrogen play a significant role in the prevention of Alzheimer's disease? J Neural Transm Suppl, 227–239.

Key TJ, Chen J, Wang DY, Pike MC and Boreham J (1990) Sex hormones in women in rural China and in Britain. Br J Cancer 62, 631–636.[Web of Science][Medline]

Khademi S and Cooke MS (2003) Comparing the attitudes of urban and rural Iranian women toward menopause. Maturitas 46, 113–121.[CrossRef][Web of Science][Medline]

Kimira M, Arai Y, Shimoi K and Watanabe S (1998) Japanese intake of flavonoids and isoflavonoids from foods. J Epidemiol 8, 168–175.[Medline]

Knight DC and Eden JA (1996) A review of the clinical effects of phytoestrogens. Obstet Gynecol 87, 897–904.[Web of Science][Medline]

Kodama M, Kodama T, Miura S and Yoshida M (1991) Nutrition and breast cancer risk in Japan. Anticancer Res 11, 745–754.[Web of Science][Medline]

Kritz-Silverstein D and Barrett-Connor E (2002) Hysterectomy, oophorectomy, and cognitive function in older women. J Am Geriatr Soc 50, 55–61.[CrossRef][Web of Science][Medline]

Kronenberg F (1990) Hot flashes: epidemiology and physiology. Ann NY Acad Sci 592, 52–86.[Web of Science][Medline]

Kronenberg F and Fugh-Berman A (2002) Complementary and alternative medicine for menopausal symptoms: a review of randomized, controlled trials. Ann Intern Med 137, 805–813.[Abstract/Free Full Text]

Ku SY, Kang JW, Kim H, Ku PS, Lee SH, Suh CS, Kim SH, Choi YM, Kim JG and Moon SY (2004) Regional differences in age at menopause between Korean–Korean and Korean–Chinese. Menopause 11, 569–574.[CrossRef][Web of Science][Medline]

Kuh DL, Wadsworth M and Hardy R (1997) Women's health in midlife: the influence of the menopause, social factors and health in earlier life. Br J Obstet Gynaecol 104, 923–933.[Web of Science][Medline]

Kurzer MS (2003) Phytoestrogen supplement use by women. J Nutr 133, 1983S–1986S.[Abstract/Free Full Text]

Kwawukume EY, Ghosh TS and Wilson JB (1993) Menopausal age of Ghanaian women. Int J Gynaecol Obstet 40, 151–155.[CrossRef][Medline]

Lam PM, Leung TN, Haines C and Chung TK (2003) Climacteric symptoms and knowledge about hormone replacement therapy among Hong Kong Chinese women aged 40–60 years. Maturitas 45, 99–107.[CrossRef][Web of Science][Medline]

Leidy LE (1994) Biological aspects of menopause: across the lifespan. Annu Rev Anthropol 23, 231–253.[CrossRef][Web of Science][Medline]

Limer JL and Speirs V (2004) Phyto-oestrogens and breast cancer chemoprevention. Breast Cancer Res 6, 119–127.[CrossRef][Web of Science][Medline]

Liu Y, Gold EB, Lasley BL and Johnson WO (2004) Factors affecting menstrual cycle characteristics. Am J Epidemiol 160, 131–140.[Abstract/Free Full Text]

Lock M (1993) Encounters with Aging: Mythologies of Menopause in Japan and North America. University of California Press, Berkeley.

Lock M (1998) Menopause: lessons from anthropology. Psychosom Med 60, 410–419.[Abstract/Free Full Text]

Lock M (2002) Symptom reporting at menopause: a review of cross-cultural findings. Journal of the British Menopause Society, 18: 132–136.

Lock M, Kaufert P and Gilbert P (1988) Cultural construction of the menopausal syndrome: the Japanese case. Maturitas 10, 317–332.[CrossRef][Web of Science][Medline]

Lu L-JW, Anderson KE, Grady JJ and Nagamani M (1996) Effects of soya consumption for one month on steroid hormones in premenopausal women: implications for breast cancer risk reduction. Cancer Epidemiol Biomarkers Prev 5, 63–70.[Abstract]

Malacara JM, Canto de Cetina T, Bassol S, Gonzalez N, Cacique L, Vera-Ramirez ML and Nava LE (2002) Symptoms at pre- and postmenopause in rural and urban women from three States of Mexico. Maturitas 43, 11–19.[Web of Science][Medline]

Manson JE, Hsia J, Johnson KC, Rossouw JE, Assaf AR, Lasser NL, Trevisan M, Black HR, Heckbert SR, Detrano R et al. (2003) Estrogen plus progestin and the risk of coronary heart disease. N Engl J Med 349, 523–534.[Abstract/Free Full Text]

Martin E (1988) Medical metaphors of women's bodies: menstruation and menopause. Int J Health Serv 18, 237–254.[Web of Science][Medline]

Marshall E (1993) Epidemiology. Search for a killer: focus shifts from fat to hormones. Science 259, 618–621.[Free Full Text]

Martin MC, Block JE, Sanchez SD, Arnaud CD and Beyene Y (1993) Menopause without symptoms: the endocrinology of menopause among rural Mayan Indians. Am J Obstet Gynecol 168, 1839–1843. Discussion 1843–1835.[Web of Science][Medline]

Maskarinec G, Nagata C, Shimizu H and Kashiki Y (2002) Comparison of mammographic densities and their determinants in women from Japan and Hawaii. Int J Cancer 102, 29–33.[CrossRef][Web of Science][Medline]

Matthews KA, Kuller LH, Wing RR and Meilahn EN (1994a) Biobehavioral aspects of menopause: lessons from the Healthy Women Study. Exp Gerontol 29, 337–342.[CrossRef][Web of Science][Medline]

Matthews KA, Wing RR, Kuller LH, Meilahn EN and Plantinga P (1994b) Influence of the perimenopause on cardiovascular risk factors and symptoms of middle-aged healthy women. Arch Intern Med 154, 2349–2355.[Abstract/Free Full Text]

Mazur W (1998) Phytoestrogen content in foods. Baillieres Clin Endocrinol Metab 12, 729–742.[CrossRef][Web of Science][Medline]

McCarthy T (1994) The prevalence of symptoms in menopausal women in the Far East Singapore segment. Maturitas 19, 199–204.[CrossRef][Web of Science][Medline]

McDonough PG (2002) The randomized world is not without its imperfections: reflections on the Women's Health Initiative Study. Fertil Steril 78, 951–956.[CrossRef][Web of Science][Medline]

McKinlay S, Brambilla D and Posner J (1992) The normal menopause transition. Maturitas 14, 103–115.[CrossRef][Web of Science][Medline]

Mei J, Yeung SS and Kung AW (2001) High dietary phytoestrogen intake is associated with higher bone mineral density in postmenopausal but not premenopausal women. J Clin Endocrinol Metab 86, 5217–5221.[Abstract/Free Full Text]

Melby MK (2005a) Vasomotor symptom prevalence and language of menopause in Japan. Menopause 12, 250–257.[CrossRef][Web of Science][Medline]

Melby MK (2005b) Factor analysis of climacteric symptoms in Japan. Maturitas doi:10.1016/j.maturitas 2005.02.002 April 1, 2005.

Meschia M, Pansini F, Modena AB, de Aloysio D, Gambacciani M, Parazzini F, Campagnoli C, Maiocchi G and Peruzzi E (2000) Determinants of age at menopause in Italy: results from a large cross-sectional study. ICARUS Study Group. Italian Climacteric Research Group Study. Maturitas 34, 119–125.[CrossRef][Web of Science][Medline]

Messina M and Hughes C (2003) Efficacy of soyfoods and soybean isoflavone supplements for alleviating menopausal symptoms is positively related to initial hot flush frequency. J Med Food 6, 1–11.[CrossRef][Medline]

Mohammad K, Sadat Hashemi SM and Farahani FK (2004) Age at natural menopause in Iran. Maturitas 49, 321–326.[CrossRef][Web of Science][Medline]

Moore B and Kombe H (1991) Climacteric symptoms in a Tanzanian community. Maturitas 13, 229–234.[CrossRef][Web of Science][Medline]

Murkies AL, Lombard C, Strauss BJ, Wilcox G, Burger HG and Morton MS (1995) Dietary flour supplementation decreases post-menopausal hot flushes: effect of soy and wheat. Maturitas 21, 189–195.[CrossRef][Web of Science][Medline]

Murkies AL, Wilcox G and Davis SR (1998) Clinical review 92: Phytoestrogens. J Clin Endocrinol Metab 83, 297–303.[Abstract/Free Full Text]

Nagata C, Takatsuka N, Kurisu Y and Shimizu H (1998a) Decreased serum total cholesterol concentration is associated with high intake of soy products in Japanese men and women. J Nutr 128, 209–213.[Abstract/Free Full Text]

Nagata C, Takatsuka N, Inaba S, Kawakami N and Shimizu H (1998b) Association of diet and other lifestyle with onset of menopause in Japanese women. Maturitas 29, 105–113.[CrossRef][Web of Science][Medline]

Nagata C, Shimizu H, Takami R, Hayashi M, Takeda N and Yasuda K (1999) Hot flushes and other menopausal symptoms in relation to soy product intake in Japanese women. Climacteric 2, 6–12.[Medline]

Nagata C, Takatsuka N, Kawakami N and Shimizu H (2001a) Soy product intake and hot flashes in Japanese women: results from a community-based prospective study. Am J Epidemiol 153, 790–793.[Abstract/Free Full Text]

Nagata C, Takatsuka N, Kawakami N and Shimizu H (2001b) Soy product intake and premenopausal hysterectomy in a follow-up study of Japanese women. Eur J Clin Nutr 55, 773–777.[CrossRef][Web of Science][Medline]

NAMS (2004) Treatment of menopause-associated vasomotor symptoms: position statement of The North American Menopause Society. Menopause 11, 11–33.[CrossRef][Web of Science][Medline]

Nestel PJ, Yamashita T, Sasahara T, Pomeroy S, Dart A, Komesaroff P, Owen A and Abbey M (1997) Soy isoflavones improve systemic arterial compliance but not plasma lipids in menopausal and perimenopausal women. Arterioscler Thromb Vasc Biol 17, 3392–3398.[Abstract/Free Full Text]

Neslihan Carda S, Bilge SA, Ozturk TN, Oya G, Ece O and Hamiyet B (1998) The menopausal age, related factors and climacteric symptoms in Turkish women. Maturitas 30, 37–40.[CrossRef][Web of Science][Medline]

Nozaki M, Koera K, Nagata H and Nakano H (2004) Hormone replacement therapy and breast cancer risk in Kyushu University Hospital: supporting the Women's Health Initiative study. J Obstet Gynaecol Res 30, 297–302.[CrossRef][Web of Science][Medline]

Obermeyer CM (2000) Menopause across cultures: a review of the evidence. Menopause 7, 184–192.[Web of Science][Medline]

Obermeyer CM, Ghorayeb F and Reynolds R (1999) Symptom reporting around the menopause in Beirut, Lebanon. Maturitas 33, 249–258.[CrossRef][Web of Science][Medline]

Obermeyer CM, Schulein M, Hajji N and Azelmat M (2002) Menopause in Morocco: symptomatology and medical management. Maturitas 41, 87–95.[CrossRef][Web of Science][Medline]

Okonofua FE, Lawal A and Bamgbose JK (1990) Features of menopause and menopausal age in Nigerian women. Int J Gynaecol Obstet 31, 341–345.[CrossRef][Medline]

Ozdemir O and Col M (2004) The age at menopause and associated factors at the health center area in Ankara, Turkey. Maturitas 49, 211–219.[CrossRef][Web of Science][Medline]

Paine BJ, Stocks NP, Ramsay EN, Ryan P and MacLennan AH (2004) Use and perception of hormone therapy following media reports of the Women's Health Initiative: a survey of Australian WISDOM participants. Climacteric 7, 143–152.[CrossRef][Web of Science][Medline]

Pan HA, Wu MH, Hsu CC, Yao BL and Huang KE (2002) The perception of menopause among women in Taiwan. Maturitas 41, 269–274.[CrossRef][Web of Science][Medline]

Panter-Brick C and Ellison PT (1994) Seasonality of workloads and ovarian function in Nepali women. Ann NY Acad Sci 709, 234–235.[CrossRef][Web of Science][Medline]

Panter-Brick C, Lotstein DS and Ellison PT (1993) Seasonality of reproductive function and weight loss in rural Nepali women. Hum Reprod 8, 684–690.[Abstract/Free Full Text]

Parkin D (1989) Cancer of the breast, endometrium, and ovary: geographical correlation. Eur J Cancer Clin Oncol 25, 1917–1925.[CrossRef][Web of Science][Medline]

Punnonen R, Jokela H, Kudo R, Punnonen K, Pyykko K and Pystynen P (1987) Serum lipids in Finnish and Japanese postmenopausal women. Atherosclerosis 68, 241–247.[CrossRef][Web of Science][Medline]

Punyahotra S, Dennerstein L and Lehert P (1997) Menopausal experiences of Thai women. Part 1: Symptoms and their correlates. Maturitas 26, 1–7.[CrossRef][Web of Science][Medline]

Ramoso-Jalbuena J (1994) Climacteric Filipino women: a preliminary survey in the Philippines. Maturitas 19, 183–190.[CrossRef][Web of Science][Medline]

Randolph JF, Jr (2002) Be careful of what you wish for: putting the WHI Estrogen/Progestin and HERS II Trials in perspective. Medscape Womens Health 7, 7.[Medline]

Randolph JF, Jr, Sowers M, Gold EB, Mohr BA, Luborsky J, Santoro N, McConnell DS, Finkelstein JS, Korenman SG, Matthews KA et al. (2003) Reproductive hormones in the early menopausal transition: relationship to ethnicity, body size, and menopausal status. J Clin Endocrinol Metab 88, 1516–1522.[Abstract/Free Full Text]

Reynolds RF and Obermeyer CM (2001) Age at natural menopause in Beirut, Lebanon: the role of reproductive and lifestyle factors. Ann Hum Biol 28, 21–29.[CrossRef][Web of Science][Medline]

Reynolds RF and Obermeyer CM (2003) Correlates of the age at natural menopause in Morocco. Ann Hum Biol 30, 97–108.[CrossRef][Web of Science][Medline]

Rizk DE, Bener A, Ezimokhai M, Hassan MY and Micallef R (1998) The age and symptomatology of natural menopause among United Arab Emirates women. Maturitas 29, 197–202.[CrossRef][Web of Science][Medline]

Robinson G (1996) Cross-cultural perspectives on menopause. J Nerv Ment Dis 184, 453–458.[CrossRef][Web of Science][Medline]

Ross PD, Norimatsu H, Davis JW, Yano K, Wasnich RD, Fujiwara S, Hosoda Y and Melton LJ, 3rd (1991) A comparison of hip fracture incidence among native Japanese, Japanese Americans, and American Caucasians. Am J Epidemiol 133, 801–809.[Abstract/Free Full Text]

Rossouw JE, Finnegan LP, Harlan WR, Pinn VW, Clifford C and McGowan JA (1995) The evolution of the Women's Health Initiative: perspectives from the NIH. J Am Med Womens Assoc 50, 50–55.[Medline]

Rossouw JE, Anderson GL, Prentice RL, LaCroix AZ, Kooperberg C, Stefanick ML, Jackson RD, Beresford SA, Howard BV, Johnson KC et al. (2002) Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results From the Women's Health Initiative randomized controlled trial. J Am Med Assoc 288, 321–333.[Abstract/Free Full Text]

Rousseau ME and McCool WF (1997) The menopausal experience of African American women: overview and suggestions for research. Health Care Women Int 18, 233–250.[Medline]

Rygwelski JM and Smith MA (1998) Dietary soy and hot flushes. J Fam Pract 46, 276–277.[Medline]

Samsioe G, Bryman I and Ivarsson E (1985) Some anthropological aspects of the climacteric syndrome. Acta Obstet Gynecol Scand Suppl 130, 5–7.[Medline]

Sanchez Perruca L, Civeira Murillo J, Martin del Moral M, Abril Garcia A and Diez Diez A (1989) Cambio social. Climaterio y depresión. Arch Neurobiol 52, 87–92.

Santoro N (2002) The menopause transition: an update. Hum Reprod Update 8, 155–160.[Abstract/Free Full Text]

Santoro N, Lasley B, McConnell D, Allsworth J, Crawford S, Gold EB, Finkelstein JS, Greendale GA, Kelsey J, Korenman S et al. (2004) Body size and ethnicity are associated with menstrual cycle alterations in women in the early menopausal transition: The Study of Women's Health across the Nation (SWAN) Daily Hormone Study. J Clin Endocrinol Metab 89, 2622–2631.[Abstract/Free Full Text]

Schwingl PJ, Hulka BS and Harlow SD (1994) Risk factors for menopausal hot flashes. Obstet Gynecol 84, 29–34.[Web of Science][Medline]

Seidl MM and Stewart DE (1998) Alternative treatments for menopausal symptoms. Systematic review of scientific and lay literature. Can Fam Physician 44, 1299–1308.[Web of Science][Medline]

Setchell KD, Brown NM and Lydeking-Olsen E (2002) The clinical importance of the metabolite equol-a clue to the effectiveness of soy and its isoflavones. J Nutr 132, 3577–3584.[Abstract/Free Full Text]

Setchell KD, Brown NM, Desai PB, Zimmer-Nechimias L, Wolfe B, Jakate AS, Creutzinger V and Heubi JE (2003) Bioavailability, disposition, and dose-response effects of soy isoflavones when consumed by healthy women at physiologically typical dietary intakes. J Nutr 133, 1027–1035.[Abstract/Free Full Text]

Shea J (1998) Revolutionary Women at Middle Age: An Ethnographic Survey of Menopause and Midlife Aging in Beijing, China. Harvard University, Doctoral dissertation.

Shimizu H, Ross RK, Bernstein L, Pike MC and Henderson BE (1990) Serum oestrogen levels in postmenopausal women: comparison of American whites and Japanese in Japan. Br J Cancer 62, 451–453.[Web of Science][Medline]

Shimizu H, Ross RK, Bernstein L, Yatani R, Henderson BE and Mack TM (1991) Cancers of the prostate and breast among Japanese and white immigrants in Los Angeles County. Br J Cancer 63, 963–966.[Web of Science][Medline]

Short R (1994) Human reproduction in an evolutionary context. In Campbell K and Wood J (eds) Human Reproductive Ecology: Interactions of Environment, Fertiliy and Behavior. pp 416–425.

Sievert LL (2003) The medicalization of female fertility—points of significance for the study of menopause. Coll Antropol 27, 67–78.[Web of Science][Medline]

Sievert LL, Freedman RR, Garcia JZ, Foster JW, del Carmen Romano Soriano M, Longcope C and Franz C (2002) Measurement of hot flashes by sternal skin conductance and subjective hot flash report in Puebla, Mexico. Menopause 9, 367–376.[CrossRef][Web of Science][Medline]

Sievert LL, Vidovic M, Horak H and Abel M (2004) Age and symptom experience at menopause in the Selska Valley, Slovenia. Menopause 11, 223–227.[CrossRef][Web of Science][Medline]

Silva I, Mor G and Naftolin F (2001) Estrogen and the aging brain. Maturitas 38, 95–100. Discussion 100–101.[CrossRef][Web of Science][Medline]

Sommer B, Avis N, Meyer P, Ory M, Madden T, Kagawa-Singer M, Mouton C, Rasor NO and Adler S (1999) Attitudes toward menopause and aging across ethnic/racial groups. Psychosom Med 61, 868–875.[Abstract/Free Full Text]

Sowers M, Crawford SL, Sternfeld B, Morganstein D, Gold EB, Greendale GA, Evans D, Neer R, Matthews K, Sherman S, et al. (2000) SWAN: A multicenter, multiethnic, community-based cohort study of women and the menopausal transition. In Lobo R, Marcus R, and Kelsey J (eds) Menopause: Biology and Pathobiology. Academic Press, San Diego, pp 175–188.

Spetz AC, Fredriksson MG and Hammar ML (2003) Hot flushes in a male population aged 55, 65, and 75 years, living in the community of Linkoping, Sweden. Menopause 10, 81–87.[Web of Science][Medline]

Staropoli CA, Flaws JA, Bush TL and Moulton AW (1998) Predictors of menopausal hot flashes. J Womens Health 7, 1149–1155.[Web of Science][Medline]

Sternfeld B, Cauley J, Harlow S, Liu G and Lee M (2000) Assessment of physical activity with a single global question in a large, multiethnic sample of midlife women. Am J Epidemiol 152, 678–687.[Abstract/Free Full Text]

van Hall E, Verdel M and van der Velden J (1998) "Perimenopausal" complaints in women and men: a comparative study. J Women's Health 3, 45–49.

Sukwatana P, Meekhangvan J, Tamrongterakul T, Tanapat Y, Asavarait S and Boonjitrpimon P (1991) Menopausal symptoms among Thai women in Bangkok. Maturitas 13, 217–228.[CrossRef][Web of Science][Medline]

Tanaka H, Date C, Chen H, Nakayama T, Yokoyama T, Yoshiike N, Iwaoka H, Iwaya M, Zaman MM, Yamaguchi M et al. (1996) A brief review of epidemiological studies on ischemic heart disease in Japan. J Epidemiol 6, S49–S59.[Medline]

Tang GW (1994) The climacteric of Chinese factory workers. Maturitas 19, 177–182.[CrossRef][Web of Science][Medline]

Tham DM, Gardner CD and Haskell WL (1998) Clinical review 97: Potential health benefits of dietary phytoestrogens: a review of the clinical, epidemiological, and mechanistic evidence. J Clin Endocrinol Metab 83, 2223–2235.[Abstract/Free Full Text]

Tice JA, Ettinger B, Ensrud K, Wallace R, Blackwell T and Cummings SR (2003) Phytoestrogen supplements for the treatment of hot flashes: the Isoflavone Clover Extract (ICE) Study: a randomized controlled trial. J Am Med Assoc 290, 207–214.[Abstract/Free Full Text]

Tominaga S and Kuroishi T (1997) An ecological study on diet/nutrition and cancer in Japan. Int J Cancer Suppl 10, 2–6.[CrossRef]

Trowell HC and Burkitt DP (1983) Western Diseases: Their Emergence and Prevention. Edward Arnold, London.

Upmalis DH, Lobo R, Bradley L, Warren M, Cone FL and Lamia CA (2000) Vasomotor symptom relief by soy isoflavone extract tablets in postmenopausal women: a multicenter, double-blind, randomized, placebo-controlled study. Menopause 7, 236–242.[Web of Science][Medline]

Valtuena S, Cashman K, Robins SP, Cassidy A, Kardinaal A and Branca F (2003) Investigating the role of natural phyto-oestrogens on bone health in postmenopausal women. Br J Nutr 89, S87–S99.[Medline]

Van Thiel DH, Galvao-Teles A, Monteiro E, Rosenblum E and Gavaler JS (1991) The phytoestrogens present in de-ethanolized bourbon are biologically active: a preliminary study in a postmenopausal woman. Alcohol Clin Exp Res 15, 822–823.[CrossRef][Web of Science][Medline]

Vitzhum V (1994) Comparative study of breastfeeding structure and its relation to human reproductive ecology. Yearbook Phys Anthropol 37, 307–349.[Medline]

Voland E (1998) Evolutionary ecology of human reproduction. Annu Rev Anthropol 27, 347–374.[CrossRef][Web of Science][Medline]

Walfisch S, Antonovsky H and Maoz B (1984) Relationship between biological changes and symptoms and health behaviour during the climacteric. Maturitas 6, 9–17.[CrossRef][Web of Science][Medline]

Washburn S, Burke GL, Morgan T and Anthony M (1999) Effect of soy protein supplementation on serum lipoproteins, blood pressure, and menopausal symptoms in perimenopausal women. Menopause 6, 7–13.[Web of Science][Medline]

Watanabe S, Zhuo X, Melby M and Ishiwata N (2005) Systematic review of intervention studies using isoflavone supplements and proposal for future studies. In Sugano (ed) Soy in Health and Disease Prevention. Marcel Dekker, New York, In press.

Whiteman MK, Staropoli CA, Benedict JC, Borgeest C and Flaws JA (2003) Risk factors for hot flashes in midlife women. J Womens Health (Larchmt) 12, 459–472.[CrossRef][Medline]

Whitten PL and Naftolin F (1998) Reproductive actions of phytoestrogens. Baillieres Clin Endocrinol Metab 12, 667–690.[CrossRef][Web of Science][Medline]

Wilbur J, Miller AM, Montgomery A and Chandler P (1998) Sociodemographic characteristics, biological factors, and symptom reporting in midlife women. Menopause 5, 43–51.[Web of Science][Medline]

Wiley AS (1998) The ecology of low natural fertility in Ladakh. J Biosoc Sci 30, 457–480.[CrossRef][Web of Science][Medline]

Wood JW (1994) Dynamics of Human Reproduction. Aldine de Gruyter, New York.

Woods NF and Mitchell ES (1999) Anticipating menopause: observations from the Seattle Midlife Women's Health Study. Menopause 6, 167–173.[Web of Science][Medline]

Worthman CM, Jenkins CL, Stallings JF and Lai D (1993) Attenuation of nursing-related ovarian suppression and high fertility in well-nourished, intensively breast-feeding Amele women of lowland Papua New Guinea. J Biosoc Sci 25, 425–443.[Web of Science][Medline]

Yamada M, Wong FL, Kodama K, Sasaki H, Shimaoka K and Yamakido M (1997) Longitudinal trends in total serum cholesterol levels in a Japanese cohort, 1958–1986. J Clin Epidemiol 50, 425–434.[CrossRef][Web of Science][Medline]

Yamamoto S, Sobue T, Kobayashi M, Sasaki S and Tsugane S (2003) Soy, isoflavones, and breast cancer risk in Japan. J Natl Cancer Inst 95, 906–913.[Abstract/Free Full Text]

Yeh A (1989) The Experience of Menopause among Taiwanese Women. East Asian Languages and Civilizations, Harvard University, Boston.

Yu H, Harris RE, Gao YT, Gao RN and Wynder EL (1991) Comparative epidemiology of cancers of the colon, rectum, prostate and breast in Shanghai, China versus the United States. Int J Epidemiol 20, 76–81.[Abstract/Free Full Text]

Zeserson JM (2001) How Japanese women talk about hot flushes: implications for menopause research. Med Anthropol Q 15, 189–205.[CrossRef][Web of Science][Medline]

Zhuo XG, Melby MK and Watanabe S (2004) Soy isoflavone intake lowers serum LDL cholesterol: a meta-analysis of 8 randomized controlled trials in humans. J Nutr 134, 2395–2400.[Abstract/Free Full Text]

Received on December 10, 2004; revised April 10, 2005; accepted on April 26, 2005

CiteULike    Connotea    Del.icio.us    What's this?

This article has been cited by other articles:

				Drospirenone in HRT? DTB, April 1, 2009; 47(4): 41 - 44. [Abstract] [Full Text] [PDF]

				Herbal medicines for menopausal symptoms DTB, January 1, 2009; 47(1): 2 - 6. [Abstract] [Full Text] [PDF]

				D. Peet Menopause and HRT InnovAiT, January 1, 2009; 2(1): 10 - 16. [Abstract] [Full Text] [PDF]

This Article Abstract FREE Full Text (PDF) All Versions of this Article: 11/5/495    most recent dmi018v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Archive Download to citation manager Search for citing articles in: ISI Web of Science (19) Request Permissions Google Scholar Articles by Melby, M. K. Articles by Kaufert, P. Search for Related Content PubMed PubMed Citation Articles by Melby, M. K. Articles by Kaufert, P. Social Bookmarking          What's this?

Online ISSN 1460-2369 - Print ISSN 1355-4786

Copyright © 2009 European Society of Human Reproduction and Embryology

Oxford Journals Oxford University Press

• Site Map
• Privacy Policy
• Frequently Asked Questions

Other Oxford University Press sites: Oxford University Press Oxford Journals China Oxford Journals Japan American National Biography Booksellers' Information Service Children's Fiction and Poetry Children's Reference Corporate & Special Sales Dictionaries Dictionary of National Biography Digital Reference English Language Teaching Higher Education Textbooks Humanities International Education Unit Law Medicine Music Online Products Oxford English Dictionary Reference Rights and Permissions Science School Books Social Sciences Very Short Introductions World's Classics