Human Reproduction Update Advance Access published online on November 24, 2009
Human Reproduction Update, doi:10.1093/humupd/dmp048
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World Health Organization reference values for human semen characteristics*,
1 Centre of Reproductive Medicine and Andrology of the University, Domagkstrasse 11, D-48129 Münster, Germany 2 Fred Hutchinson Cancer Research Center, SCHARP Statistical Center for HIV/AIDS Research and Prevention, Seattle, WA, USA 3 UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), Department of Reproductive Health and Research, WHO, CH-1211 Geneva 27, Switzerland 4 Service d'Histologie-Embryologie, Biologie de la Reproduction/CECOS, Pavillon Cassini, Hôpital Cochin, Paris, France 5 Department of Obstetrics and Gynaecology, University of Melbourne, Royal Women's Hospital, Carlton, VIC, Australia 6 Center for Reproductive Medicine and Andrology, University Hospital Halle, Martin Luther University, Halle, Germany 7 Faculty of Health Sciences, Oslo University College, Oslo, Norway 8 Reproductive Biology Unit, Stellenbosch University, Tygerberg, South Africa 9 Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, CA, USA
To whom correspondence should be addressed at: 10 Correspondence address. Tel: +49-251-835-6449; Fax: +49-251-835-6093; E-mail: tgcooper{at}gmx.de
BACKGROUND: Semen quality is taken as a surrogate measure of male fecundity in clinical andrology, male fertility, reproductive toxicology, epidemiology and pregnancy risk assessments. Reference intervals for values of semen parameters from a fertile population could provide data from which prognosis of fertility or diagnosis of infertility can be extrapolated.
METHODS: Semen samples from over 4500 men in 14 countries on four continents were obtained from retrospective and prospective analyses on fertile men, men of unknown fertility status and men selected as normozoospermic. Men whose partners had a time-to-pregnancy (TTP) of 
12 months were chosen as individuals to provide reference distributions for semen parameters. Distributions were also generated for a population assumed to represent the general population.
RESULTS: The following one-sided lower reference limits, the fifth centiles (with 95th percent confidence intervals), were generated from men whose partners had TTP 12 months: semen volume, 1.5 ml (1.4–1.7); total sperm number, 39 million per ejaculate (33–46); sperm concentration, 15 million per ml (12–16); vitality, 58% live (55–63); progressive motility, 32% (31–34); total (progressive + non-progressive) motility, 40% (38–42); morphologically normal forms, 4.0% (3.0–4.0). Semen quality of the reference population was superior to that of the men from the general population and normozoospermic men.
CONCLUSIONS: The data represent sound reference distributions of semen characteristics of fertile in a number of countries. They provide an appropriate tool in conjunction with clinical data to evaluate a patient's semen quality and prospects for fertility.
Key words: human semen / reference values / infertility diagnosis / fertile men
* Dedicated to the memory of Professor GMH Waites (1928–2005).
The list of authors who contributed data to this study is given in the Appendix.
These authors (M.T.M., K.M.V.) are staff members of the World Health Organization. The authors alone are responsible for the views expressed in this publication; these views do not necessarily represent the decisions or policies of the World Health Organization.
Received on January 23, 2009; revised September 7, 2009; accepted on September 21, 2009