Semen Analysis, Explained

Parameter explainer · Movement

Motility: count the swimmers, not the percentage

Motility arrives as a percentage, which hides the number that outcome studies actually use. One multiplication turns your three main values into it.

Total, progressive, and the one calculation that matters

Motility is the share of sperm that are moving. Progressive motility counts only the ones swimming forward; total motility also counts those moving in place or in circles. The WHO 2021 manual brought back a four-grade system (rapidly progressive, slowly progressive, non-progressive, immotile), though many reports still show three.[2]

The figure outcome studies lean on is the total motile sperm count (TMSC): volume × concentration × total motility. It answers the question people actually have: how many moving sperm were in the whole sample.

Example: 3 mL × 20 million/mL × 40% motility = 24 million motile sperm. Each number alone looks "borderline"; together they land in the 20-million-plus band that behaved like normal in a 1,177-couple cohort. The numbers box does this arithmetic for you.

Where your value sits

WHO 2021 distribution for total motility (%). Example marker at 40%.
Measure5th25th50th75th95th
Total motility (%)4255647281
Progressive motility (%)3043556272
Immotile (%)2027354556
Vitality (% live)5465798897

Note the immotile row: the median fertile man has 35% of his sperm not moving at all.[1] The total motility limit moved from 40% to 42% in 2021 and the progressive limit from 32% to 30%, so older reports print different lines.[2] There is no WHO reference limit for TMSC; the bands below come from outcome studies.

What it predicts, and what it does not

In 6,061 men, progressive motility of 50% or more and a total progressive motile count of 40 million or more were associated with faster conception (hazard ratios about 1.5 to 1.6). As with count, these "optimal" values sit far above the WHO 5th centile.[3] In 1,177 couples followed three years, prewash TMSC bands of under 5, 5–20 and over 20 million separated spontaneous pregnancy chances better than any single WHO parameter; over 20 million was treated as normal.[4] In the fertile-versus-infertile comparison, motility above 63% was "fertile range" and below 32% "subfertile range," with large overlap.[5]

For IUI, the number that matters is the motile count after the lab washes the sample. In 1,287 cycles, pregnancy rates fell only when fewer than 5 million motile sperm were inseminated.[6] Proposed prewash TMSC thresholds for IUI range from about 2 to 10 million across studies and remain contested.[7]

A motility value below 42% does not mean the sperm cannot fertilize. Near-total immotility (close to 0%) is a different situation and needs its own work-up; see the red flags below.

Why handling and timing change the number

Motility is measured within about an hour of collection, at body temperature. Delays, cold, and the wrong container all lower it on the day.[2] Abstinence length moves it the other way from count: across 13 randomized trials, samples after under 2 days of abstinence had about 4 points higher progressive and total motility (and lower DNA fragmentation) than samples after 3 or more days, at the cost of lower concentration.[8] Within-man variation is large for every parameter, and at least three samples were needed to characterize a man reliably in the largest variability study.[9] Guidelines ask for two analyses, about a month apart, when the first is abnormal.[10][11]

When total motility is under about 40%, the manual recommends a vitality test, which tells dead sperm apart from live sperm that cannot swim. The distinction changes what comes next.[2]

What can lower it

FactorWhat the evidence showsStrength
Delay to analysis, cold, long abstinencePre-analytical; short abstinence +4 points progressive motility.[8]Moderate (RCTs)
Clinical varicoceleRepair associated with about +10 to +12 points motility in pooled studies; pregnancy RR 1.55, low certainty.[12][13]Low to moderate
White cells in semen, genital-tract infectionAssociated with reduced motility; clinical weight debated; WHO threshold 1 million leukocytes/mL.[17]Low
Antisperm antibodies (after vasectomy reversal, trauma, infection)Can cause clumping and reduced forward progression.[17]Low
Smoking−3.5 points motility in smokers across 20 studies.[15]Moderate (observational)
Scrotal heatTwice-weekly sauna for 3 months impaired motility; reversed by 6 months after stopping.[16]Low (n=10)
Flagellar or ciliary defectsNear-total immotility with live sperm; ask about chronic sinus or chest infections.[17]Specialist

What guidelines say to do next

  1. Repeat under standard conditions: 2–7 days of abstinence, kept the same between tests, complete collection, analysis within an hour.[11]
  2. Compute TMSC from the three numbers. Isolated, mildly low motility with a TMSC above 20 million is the lowest-concern pattern.[4]
  3. Vitality test if total motility is under about 40%.[2]
  4. Physical exam for varicocele; consider repair if palpable with abnormal semen parameters; not for subclinical varicocele.[10][11]
  5. Hormone tests are indicated when concentration is also low, rather than for isolated low motility.[10]
  6. Treatment route: low TMSC on repeated tests leads to a discussion of IUI versus IVF/ICSI with expected post-wash counts (Statement 39). Near-total immotility goes to a specialist pathway.[10]
  7. Not recommended: testosterone while trying; supplements as a fix (Cochrane 2022: very-low-certainty signal that disappears when biased trials are excluded); routine DNA fragmentation testing at the first visit.[10][14]

Ask for a prompt specialist review if: total motility is near 0%; motility, count and morphology are all low; the report notes clumping or many white cells; there is pain, fever or urinary symptoms; or you have used testosterone, anabolic steroids or SARMs.

Questions to bring to your doctor

  • What is my total motile sperm count, and where does it sit against 5 and 20 million?
  • How long after collection was the sample analysed, and could handling have lowered the motility?
  • Was progressive motility reported separately from total? Which one was low?
  • If total motility was under 40%, was a vitality test done? Are the non-moving sperm alive?
  • Were white cells or clumping noted? Do I need an infection or antibody work-up?
  • Did the exam find a varicocele, and is it palpable?
  • If we consider IUI, what post-wash motile count would you expect, and is it above 5 million?
  • What abstinence length should I use for the repeat, and should I keep it the same as last time?

Things people hear, and what the evidence says

"Motility 35% means only a third of my sperm work."
The median fertile man has 35% immotile sperm. What matters is the number of moving sperm in the whole sample, not the percentage alone.
"Tight underwear and laptops ruined my motility."
Heat can lower motility, but the documented sauna effect reversed within months. It is a reason to change a habit, not a diagnosis.
"Carnitine or CoQ10 fixed my motility."
Cochrane 2022 found very-low-certainty evidence that becomes null once biased trials are removed. A jump between two tests is usually normal variation plus handling.
"Progressive motility 25% is a failing grade."
The WHO 5th centile (30%) is a reference point from fertile men, not a pass/fail line; the WHO says a single value below it is not a diagnosis.

Sources

Each claim above carries a bracketed number pointing here. "Primary" means the full paper or guideline text was read; "abstract" means the abstract; "via review" means the figure was taken from a named review.

  1. WHO 6th-edition reference distributions, reproduced in PMC — primary table. https://pmc.ncbi.nlm.nih.gov/articles/PMC12539902/table/t1/
  2. Boitrelle F et al. Critical review of the WHO 6th edition. Life 2021 — primary. https://pmc.ncbi.nlm.nih.gov/articles/PMC8706130/
  3. Semen parameter thresholds and time-to-conception in 6,061 men. Hum Reprod 2021 — primary. https://academic.oup.com/humrep/article/36/8/2121/6294420
  4. Hamilton JA et al. Total motile sperm count: a better indicator. Hum Reprod 2015 — primary. https://academic.oup.com/humrep/article-lookup/doi/10.1093/humrep/dev058
  5. Guzick DS et al. NEJM 2001 — primary. https://www.nejm.org/doi/full/10.1056/NEJMoa003005
  6. IUI outcomes by inseminated motile count; 1,287 cycles. PLOS ONE 2025 — primary. https://pmc.ncbi.nlm.nih.gov/articles/PMC11922279/
  7. Review of TMSC thresholds for IUI — primary review. https://pmc.ncbi.nlm.nih.gov/articles/PMC9790824/
  8. Abstinence duration and semen parameters: meta-analysis of 13 RCTs. Front Endocrinol 2024 — primary. https://www.frontiersin.org/articles/10.3389/fendo.2024.1373426/full
  9. Keel BA. Within- and between-subject variation. Fertil Steril 2006 — abstract. https://pubmed.ncbi.nlm.nih.gov/16412742/
  10. AUA/ASRM Guideline on Male Infertility (2024 amendment) — primary. https://www.auanet.org/guidelines-and-quality/guidelines/male-infertility
  11. EAU Guidelines: Male Infertility — primary. https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/male-infertility
  12. Agarwal A et al. Varicocelectomy meta-analysis (figures quoted in PMC) — secondary. https://pmc.ncbi.nlm.nih.gov/articles/PMC4770486/
  13. Persad E et al. Varicocele treatment. Cochrane 2021 — abstract. https://pubmed.ncbi.nlm.nih.gov/33890288/
  14. de Ligny W et al. Antioxidants for male subfertility. Cochrane 2022 — primary. https://pmc.ncbi.nlm.nih.gov/articles/PMC9066298/
  15. Sharma R et al. Smoking and semen quality: meta-analysis. Eur Urol 2016 — abstract. https://pubmed.ncbi.nlm.nih.gov/27113031/
  16. Garolla A et al. Sauna exposure and sperm parameters. Hum Reprod 2013 — abstract. https://pubmed.ncbi.nlm.nih.gov/23411620/
  17. Causes of asthenozoospermia: narrative review — primary review. https://pmc.ncbi.nlm.nih.gov/articles/PMC3093801/

Concentration and total count

The floor, the plateau, and the thresholds that trigger hormone and genetic tests.

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How to read your report

Every line on the report, with WHO 2021 ranges and a glossary.

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