My semen analysis is abnormal

Where the numbers come from

The reference limits on your report are not a definition of normal. They are the fifth centile of more than 4,500 men from fourteen countries whose partners had conceived within twelve months — men, in other words, of proven fertility.¹

That produces the familiar lower limits: 15 million sperm per millilitre, 39 million in the whole ejaculate, 32% progressive motility, and 4% normal forms.¹ A follow-up analysis using data through 2020 found these values still broadly hold, and its authors were explicit that they describe a distribution rather than a boundary between fertile and infertile men.²

The arithmetic matters. If the limit is the fifth centile of proven-fertile men, then one in twenty men who have just fathered a child falls below it. A result under the line is not a diagnosis of infertility. It is a position on a curve.

Then why does it feel like a pass mark?

Because it is printed like one, and because the lines have moved.

When the WHO lowered its reference values in 2010, roughly 15% of men previously classified as abnormal became normal overnight, without anything changing in their bodies.³ When the values were revised again in 2021, about one man in three was reclassified in the worse direction compared with the 2010 criteria — and those men did have measurably poorer clinical, hormonal and reproductive outcomes, so the tightening was not arbitrary.⁴

Two men with identical samples, tested a decade apart, could therefore receive opposite verdicts. That is a good reason to treat the category as a prompt for assessment rather than as a result in itself.

What each parameter actually predicts

They are not equal, and the differences are useful.

Concentration carries the most weight. In a study of 358 men from the general population it was the single most significant predictor of fertility, and motile sperm concentration was the strongest predictor of all.⁵ In 71,623 infertile men in China it was again the best predictor of assisted-conception outcomes, ahead of motility.⁶

Morphology adds something concentration does not. In the largest direct comparison of fertile and infertile men — 765 infertile and 696 fertile — morphology showed the greatest discriminatory power of the three conventional measures.⁷ The proportion of normally formed sperm predicted pregnancy independently of how many there were.⁸

Motility is the most contested. A prospective study of 430 couples planning a first pregnancy found volume and motility of limited value in predicting conception,⁸ while computer-assisted measurement of motility did predict fertility in general-population men.⁵ The likely explanation is that machines see things the eye does not.

And there is a ceiling. In those 430 couples, the chance of conception per cycle rose with sperm concentration up to about 40 million per millilitre and then stopped rising.⁸ Beyond that point, more sperm did not mean more pregnancies.

The most important fact on this page

A single semen analysis is not your baseline.

Semen parameters vary enormously within the same man from week to week. The within-subject coefficient of variation for sperm count is 54.2% in men attending a fertility clinic and 45.8% even in screened donors.⁹ A study of repeat samples found that one sample gives a positive predictive value of only 43 to 91% for correctly classifying a man; the average of two samples is needed to reach 86–100%.¹⁰

Put plainly: a man can produce a result below the limit one month and comfortably above it the next, having done nothing differently. The WHO recommends at least two samples before drawing conclusions, and in practice a single reassuring result often stops the process — which risks missing men who should have been investigated.¹⁰

If a first result has frightened you, the correct next step is very often simply to repeat it.

What legitimately shifts the numbers

Abstinence. A dose-response meta-analysis of 85 studies found that longer abstinence raises volume and total count but tends to lower progressive motility, with the balance best at around two to seven days.¹¹ An analysis of 23,527 samples found men with normal parameters gain from longer abstinence, while those with motility or morphology problems may do better with shorter intervals.¹² Very long abstinence is also associated with more DNA fragmentation.¹³

Age. In 2,612 men, total motility, progressive motility and normal morphology all declined with age, becoming clinically significant after about forty.¹⁴ Progressive motility appears to fall earliest, with one large study identifying a threshold near twenty-eight.⁶

Weight. Here the evidence genuinely disagrees. A meta-analysis of fourteen studies and 8,443 men found differences across BMI categories in every parameter;¹⁵ a cross-sectional study of 511 men found no association except with morphology.¹⁶ The largest analysis — 28,167 infertile men — found an inverted U, with semen quality peaking around a BMI of 26 and falling either side.¹⁷

Recent illness, fever and short-term stressors also matter, which is another argument for repeating the test rather than acting on one number.

What if everything is normal and we still cannot conceive?

This is commoner than the report implies. Conventional analysis cannot reliably predict pregnancy or separate fertile from infertile men except at the extremes,¹⁸ and up to 15% of infertile men have entirely normal conventional parameters.⁶

The test measures how many sperm there are, how they move and what they look like. It does not measure whether they can fertilise an egg, whether their DNA is intact, or how they behave in the female reproductive tract.¹⁹ That is the honest limit of the technology, and it is why a normal result should not end the conversation if you have been trying for a long time.

Where DNA fragmentation testing fits is a separate question, and a more commercially contested one — I have written about it in its own note.

An unexpected finding worth knowing

Semen quality appears to be a marker of general health, not only of fertility.

In 78,284 men followed for up to fifty years, men with a total motile sperm count above 120 million could expect to live 2.7 years longer than men with counts between zero and five million, with a dose-response relationship across all semen parameters and all-cause mortality that persisted after adjustment for education and prior diagnoses.²⁰

This does not mean a low count shortens your life. It more likely means that whatever produces good sperm production — vascular health, hormonal balance, absence of chronic disease — also produces longevity. But it is a reason to treat an abnormal result as a prompt to look at your general health, rather than only at your fertility.

How strong is the evidence?

Strong at population level, weak at the level of the individual man.

The epidemiology here is unusually good: cohorts of tens of thousands, meta-analyses aggregating hundreds of studies. What all of it establishes is a probability distribution. What none of it does is tell a particular man whether he will conceive. The overlap between fertile and infertile populations is substantial on every parameter, and the studies say so themselves.⁷¹⁸

The weakest area is BMI, where large studies contradict each other outright.¹⁵¹⁶¹⁷ The strongest are the reference-value derivation¹ and the within-man variability data,⁹¹⁰ which are the two facts most likely to change what you do next.

Bottom line

Your result is a position on a distribution of men who have already fathered children, measured once, in a sample that varies by half its own value from month to month.

Read it that way and the sensible next steps follow: repeat the test before concluding anything, have a physical examination — which finds things no sample can — and treat any abnormality as a reason to look at your general health as well as your fertility.

Almost every man I see with an abnormal result has already decided what it means, usually from a single printout and an evening online. One test is a starting point, not a verdict — and repeating it properly, with a proper examination alongside, changes the picture more often than men expect.