Semen Analysis Parameters
WHO 2021 Sixth Edition Reference Values
Evidence grade 5 of 5, Settled. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Laboratory test; not an FDA-regulated drug
Reference only. Not medical advice.
This is something to take to a clinician. The Atlas can tell you what is known about semen analysis parameters in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Semen analysis is the foundational laboratory test in evaluating male fertility, measuring volume, sperm concentration, total count, motility, and morphology. The World Health Organization published its sixth-edition laboratory manual in 2021, deriving lower reference limits from roughly 3,500 fertile men across 12 countries whose partners conceived naturally within 12 months. These limits describe the 5th centile of a fertile population; they are not a hard threshold separating fertile from infertile men.
The cornerstone of the male fertility workup, and the most misunderstood number in men's health.
What people take it for
What it is taken for. Approval, where it exists, covers only some of these.
How it works
A semen sample, ideally collected after 2-7 days of abstinence, is examined within an hour. Concentration and motility are assessed microscopically (increasingly with computer-assisted sperm analysis), morphology is scored against strict criteria, and additional tests such as vitality, leukocyte staining, and round-cell quantification may be added. Because spermatogenesis spans roughly 72-90 days, results reflect testicular events from weeks to months earlier, and at least two samples weeks apart are recommended before drawing conclusions.
What the single number hides
The WHO reference limits are percentiles of men who fathered children, not diagnostic cutoffs. A result below the 5th centile does not equal sterility, and a result above it does not guarantee fertility. The 2021 edition lowered or shifted several limits versus the 2010 fifth edition, meaning some men previously labeled abnormal are now within range without any biological change. Critics, including authors of a 2022 Human Reproduction reappraisal, note the reference cohort's geographic and methodological limitations. the Atlas presents these as population statistics, not a Ēnel verdict on any individual.
What people get wrong
Often saidA 'low' count below the reference limit means a man is infertile
ActuallyThe limits are the 5th centile of fertile men. Many men below the cutoff conceive naturally, and the result must be interpreted alongside the partner's fertility and repeat testing.
Often saidOne abnormal sample is definitive
ActuallySperm parameters vary substantially over time and with abstinence interval, illness, and fever. Guidelines call for at least two samples before conclusions.
Often saidMorphology of 4% normal means 96% of sperm are 'broken'
ActuallyStrict (Kruger) morphology is an intentionally stringent standard; 4% normal forms is the lower reference limit among fertile men, not a sign of failure.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
How we got here
Crude sperm counting dates to the 19th century, but standardized methodology arrived with the WHO laboratory manuals, first published in 1980 and revised in 1987, 1992, 1999, 2010, and 2021. The 2010 fifth edition was a turning point because it abandoned arbitrary historical thresholds in favor of evidence-based percentiles from men with proven fertility. The 2021 sixth edition expanded the reference dataset and added detail on advanced and research-level assays such as DNA fragmentation and oxidative stress.
- 1980First WHO semen analysis manual published
- 2010Fifth edition introduces percentile-based reference limits from fertile men
- 2021Sixth edition expands reference cohort and updates lower limits
What we do not know
- How well do strict morphology percentages predict natural conception?
- Should DNA fragmentation be a routine parameter rather than an add-on?
- Do the 2021 reference cohorts generalize across all populations?
At a glance
- Sperm concentration (5th centile)
- 16 million/mL
- Total sperm number
- 39 million/ejaculate
- Total motility
- 42%
- Progressive motility
- 30%
- Normal morphology
- 4%
- Semen volume
- 1.4 mL
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Semen Analysis Parameters. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- What can go wrong. We have not written the risk line for this one. Read the safety section below rather than treating its absence as reassurance.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
WHO laboratory manual for the examination and processing of human semen, 6th edition2021
Established current lower reference limits (concentration 16 million/mL, total motility 42%, 4% normal morphology) from approximately 3,500 fertile men in 12 countries
Cooper et al., WHO 5th edition reference values2010
First WHO manual to derive limits from a defined fertile reference population, establishing the percentile-based framework continued in 2021