Press release

Dundee sets new WHO global standards in male reproductive health

Published on 27 July 2021

A University of Dundee researcher has produced the most detailed representation to date of a fertile man, information that will be used to help couples across the globe conceive.

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Dr Martin Campbell, a clinical lecturer within Dundee’s School of Medicine, was tasked with updating the World Health Organisation (WHO) guidelines for semen assessment values. His findings will be adopted as the global benchmark for the semen parameters of a fertile male and used to help clinicians direct diagnostic or therapeutic interventions for couples experiencing infertility.

Sperm counts have declined globally in recent decades, contributing to a growing crisis in male reproductive health. Male factor fertility is now implicated in approximately 40% of couples experiencing infertility, and poor sperm count is associated with overall morbidity and mortality.

A semen analysis is one of the first tests carried out when couples seek help to conceive. The WHO determines fertility as the ability to achieve a pregnancy within one year of trying to conceive. The ‘normal ranges’ for a sperm count and other parameters, must then reflect a reference population that are able to achieve this.  Estimates suggest that between 48 million couples and 186 million individuals live with infertility globally.

Dr Campbell examined an array of research on semen parameters published over the past two decades. This data comprised samples from more than 3500 men from 12 countries across five continents, a more detailed and diverse population than that which informed the previous WHO guidelines.

He found the semen parameters of a fertile man to be a sperm concentration greater than or equal to (≥) 16 million/ml, progressive motility ≥30%, total motility ≥ 42% and normal forms ≥ 4%. While these distributions in couples achieving a pregnancy within 12 months do not differ greatly from those published in 2010, Dr Campbell’s findings, being more geographically representative and featuring a significantly increased number of subjects, will provide increased confidence in the robustness of the guidelines.

“There is a recognised global crisis in male fertility, but what does this actually mean for the couple or male in a fertility clinic?” he said. “The patient is keen to know if his semen analysis is ‘within fertile limits’ and the next step in the journey will be guided by the man’s sperm count.

“Having relevant and up to date reference values of a semen analysis against the backdrop of globally declining sperm counts is required to help determine whether a couple is likely to conceive naturally or whether they may require treatment to achieve pregnancy. Those presenting for assessment of fertility can be confident that investigations and treatments are recommended by their clinician on the basis of the most up to date and robust research.”

Although this study establishes more comprehensive and globally applicable reference values for semen parameters of fertile men, they do not represent distinct limits between fertile and subfertile men.

Dr Campbell hopes to encourage continual assessment of the fertile male by hosting his dataset on Discovery - the University of Dundee Research Portal and allowing researchers from around the world to examine and add to it as appropriate.

This research will be utilised for future research into male reproductive health as well as influencing clinical decisions. Dr Campbell’s research was originally published in the journal Andrology and now forms part of the latest edition of the WHO laboratory manual for the examination and processing of human semen, which is launched today.

He carried out the research while working as a Scottish Clinical Research Excellence Development Scheme (SCREDS) clinical lecturer at Dundee. SCREDS provides an integrated training and career development pathway enabling clinicians to pursue academic and clinical training within the NHS.


Jonathan Watson

Senior Press Officer

+44 (0)1382 381489