Male Fertility Myths: What Most People Get Wrong About a Man's Role in Conception

When a couple struggles to conceive, the investigation almost always starts with the woman. Blood tests, hormone panels, ultrasounds, cycle monitoring — and often months pass before anyone asks about the male partner.

This is one of the most consistent inefficiencies in how fertility challenges are handled. Male factor is involved in approximately 40–50% of all infertility cases. Yet male fertility remains significantly under-tested, under-discussed, and surrounded by myths that either create false confidence or unnecessary shame.

Here is what the evidence actually shows — about five of the most persistent male fertility myths.

Myth 1: If a Man Is Healthy, His Fertility Is Fine

This is the most consequential myth, because it is the one that delays investigation most often.

Male fertility — specifically, sperm quality — produces no symptoms. A man with a significantly low sperm count, poor motility, or high DNA fragmentation will feel completely normal. There is no pain, no visible sign, no functional difference in day-to-day life. The only way to know whether sperm quality is adequate is to test it.

A semen analysis measures count (how many sperm are present), motility (what percentage are moving and moving well), morphology (what percentage have a normal shape), and volume. All four parameters matter. A man with a healthy lifestyle and no medical history can have any of these parameters affected — and would have no way of knowing without a test.

The implication: both partners should be tested from the start of a fertility investigation, regardless of how healthy the man appears.

Myth 2: Male Fertility Does Not Decline With Age

Female fertility and age is well-documented. Male fertility and age is much less discussed — and the evidence is more significant than most people realise.

From the mid-30s, sperm DNA fragmentation — the proportion of sperm with damaged genetic material — increases progressively with age. This affects more than just count: higher DNA fragmentation is associated with lower fertilisation rates, higher miscarriage rates, and longer time to conception even when conventional semen parameters look normal.

Studies also show that men over 40 contribute to higher rates of pregnancy loss and longer time to pregnancy compared to men in their 20s, even when partnered with women of the same age.

This is not a reason for alarm. It is a reason to include age in the picture when both partners are being assessed — and not to assume the male side of the equation is automatically unaffected by time.

Myth 3: Sperm Count Is the Only Number That Matters

A semen analysis reports multiple parameters. Of these, count — the total number of sperm — receives the most attention. But count alone is a poor predictor of fertility potential.

Motility — the percentage of sperm that are moving, and moving progressively forward — is at least as important as count. A high count of poorly motile sperm is less useful than a moderate count of well-motile sperm.

Morphology — the percentage of sperm with a normal shape — affects the sperm's ability to penetrate an egg. The normal threshold is surprisingly low: most labs consider 4% normal morphology to be within the acceptable range, which means even fertile men have a large proportion of morphologically abnormal sperm.

DNA fragmentation — not included in a standard semen analysis but available as an add-on test — measures genetic integrity. High DNA fragmentation can cause conception difficulty and miscarriage even when count, motility, and morphology are all normal.

Interpreting a semen analysis well means looking at all parameters together — and understanding what they mean for the couple's specific situation.

Myth 4: A Man Who Has Fathered a Child Before Is Still Fertile

Male fertility is not static. It changes over time — affected by age, health changes, new medications, infections, varicoceles that develop, and other factors.

A man who fathered a child five or ten years ago may have a meaningfully different sperm profile today. This is particularly relevant in couples where the male partner has had recent significant health changes (illness, surgery, sustained high fever, new medications) or where the couple has been together for several years and trying for more than one.

Previous fatherhood is relevant medical history. It is not a guarantee of current fertility.

Myth 5: Tight Underwear Is a Major Cause of Male Infertility

This one gets outsized attention. Scrotal temperature regulation — the reason the testes sit outside the body — does matter for sperm production. And sustained heat exposure (long-distance cycling, hot baths, occupational heat exposure) has been shown to have modest effects on sperm parameters.

But the effect of underwear choice, in the absence of other heat stressors, is marginal. Studies comparing briefs and boxers show small and inconsistent differences that are unlikely to be clinically meaningful in most situations.

For men with otherwise normal sperm parameters, switching underwear will not make a meaningful difference. For men with compromised parameters, addressing the underlying cause — whether structural, hormonal, or lifestyle-related — matters far more than fabric choices.

The Straightforward Starting Point

A basic semen analysis is a non-invasive test that takes a few minutes and can be arranged quickly. It provides more information about male fertility than years of assumptions.

If you and your partner are investigating fertility challenges, arranging a semen analysis at the same time as the initial female investigations is the most efficient approach. It ensures that both sides of the equation are understood from the beginning — rather than discovering a male factor months into a female-focused investigation.

A free fertility assessment can help map what investigations make sense for both of you as a starting point.