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Evidence Library · The male half

A semen analysis is not a pass or fail

The WHO manual that publishes the numbers says so itself, in one sentence.

The reference values everybody quotes come from the sixth edition of the WHO laboratory manual. They are the fifth centile of results from more than 3,500 men across twelve countries whose partners conceived naturally within a year.

MeasureFifth centileMedian in the same men
Volume1.4 mL3.0 mL
Concentration16 million per mL66 million per mL
Total count39 million per ejaculate210 million
Total motility42%64%
Progressive motility30%55%
Normal forms4%14%
The manual's own warning, verbatimThe lower fifth percentile of data from men in the reference population (Table 8.3) does not represent a limit between fertile and infertile men.

And, from the same manual: For an individual patient, a semen analysis is never prognostic of fertility, as it is the fertility potential of the couple that defines them as fertile or subfertile.

The manual explains why in plain terms. Some couples conceive naturally within a year despite problems in the ejaculate. Other men with entirely normal results are classed as infertile because the difficulty is elsewhere. There is, in the manual's words, a substantial overlap of semen examination results between fertile and infertile men.

A result just below the fifth centile means you are in the lowest 5% of a group of men who all became fathers. That is a reason to look further. It is not a diagnosis, and it is certainly not a verdict.

Where this comes from:
26. World Health Organization. WHO laboratory manual for the examination and processing of human semen. 6th ed. Geneva: World Health Organization; 2021.
27. Campbell MJ, Lotti F, Baldi E, Schlatt S, Festin MPR, Björndahl L, et al. Distribution of semen examination results 2020: a follow up of data collated for the WHO semen analysis manual 2010. Andrology. 2021;9(3):817-822.

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