Abstract
It is now 11years since publication of the WHO 2010 guidelines for semen assessment values, and it is critical to determine whether they are still valid and/or whether they should be modified. To utilise data published since 2010 and combine these with data used in the 2010 assessment to provide an updated and more comprehensive representation of the fertile man. This may be utilised to present an updated distribution of values for use by WHO in 2021. Two specific analyses were performed namely, (1) Analysis 1: Examination of published data following publication of WHO 2010 [termed 2010-2020 data]. (2) Analysis 2: Examination of the data used to help formulate the 2010 distribution of values combined with the data from Analysis (1) [termed WHO 2020]. In total, data from more than 3500 subjects, from twelve countries and five continents were analysed. The 5th centile values for concentration, motility and morphology are: 16×106 /ml, 30% progressive motility [42% total motility] and 4% normal forms. This study presents substantial additional information to establish more comprehensive and globally applicable lower reference values for semen parameters for fertile men although they do not represent distinct limits between fertile and subfertile men. There are still data missing from many countries and, some geographical regions are not represented. Moreover, the number of subjects although significant is still relatively low (<4000). These distributions of values now include semen analysis providing a more global representation of the fertile man. Increasing the number of subjects provides robust information that is also more geographically representative.
Highlights
The World Health Organisation (WHO) published the first laboratory manual for the examination of human semen and semen- cervical mucus interaction in 1980 (WHO 1980), the 5th Edition[1] was the first to present distribution of semen parameter values that were based on significant supporting data.[2]
TA B L E 2 Distribution of semen parameters for the fertile man and the 95% confidence intervals (CI) for the 5th centile, collated from published sources used in Analysis 1: 2010–2020 data
This study presents substantial additional information to establish more comprehensive and globally applicable data for semen parameters
Summary
The World Health Organisation (WHO) published the first laboratory manual for the examination of human semen and semen- cervical mucus interaction in 1980 (WHO 1980), the 5th Edition[1] was the first to present distribution of semen parameter values that were based on significant supporting data.[2] These were defined from a population-based analysis of fertile men namely those with current or formerly pregnant partners with a known Time to Pregnancy (TTP) up to and including 12 months.[2] The 5th centiles were presented as the lower reference values[1,2] and, as expected, these have been ubiquitously used in the literature and clinical practice. We present substantial additional data obtained from published sources to potentially formulate more comprehensive and up to date lower reference values These new data, combined with the previous information, comprises a database of semen analysis results of >3500 subjects, from twelve countries and five continents.
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