Sperm Also Ages: Men Over 45 Have 31% More Genetic Mutations 2026

Sperm also ages, and men over 45 have 31% more genetic mutations in their sperm compared to men under 30, according to a new study presented by the IVI Foundation at the 42nd Annual Meeting of the European Society of Human Reproduction and Embryology. The finding challenges the long-held belief that only women need to worry about their biological clock when having children.

Historically, the classic biological argument focused on the finite ovarian reserve and cellular aging of oocytes. But evidence has been warning for years that time also runs for men. This new research puts a concrete figure on male reproductive aging.

Why Sperm Mutations Increase with Age

Unlike oocytes, which form during female embryonic development and remain dormant until ovulation, sperm are produced continuously from puberty onward. This means the stem cells that give rise to sperm are constantly dividing, allowing even a 70-year-old man to continue producing sperm.

In cell biology, each division is an opportunity for a DNA copying error. While cellular repair mechanisms are remarkably efficient, they are not perfect. Over decades, errors accumulate. The study quantifies this: men over 45 show a 31% increase in sperm mutations compared to younger men.

This isn't about a man's ability to father a child—fertility may persist—but about the genetic quality of the sperm. The mutations can have implications for offspring health, including risks of certain genetic disorders.

What the Study Found

The IVI Foundation's research adds to a growing body of evidence that paternal age matters. The 31% figure is a clear, measurable difference that clinicians can use when counseling couples.

The study was presented at the 42nd Annual Meeting of the European Society of Human Reproduction and Embryology, a leading forum for reproductive science. While the abstract likely focuses on the mutation rate, the broader context is that sperm quality declines with age, not just quantity.

• Men over 45 have 31% more sperm mutations than men under 30.
• Sperm production is continuous, leading to cumulative DNA copying errors.
• Paternal age is an independent factor in offspring genetic health.
• Fertility may persist, but genetic quality declines with age.
• Couples planning pregnancy should consider both partners' ages.

How This Compares to Female Reproductive Aging

Female reproductive aging is well-known: oocyte quality and quantity decline sharply after age 35, leading to increased difficulty conceiving and higher risk of chromosomal abnormalities. Male aging is more gradual but still significant.

The table below summarizes key differences in reproductive aging between men and women. Context on how this played out before sits in Sperm Also Ages: Men Over 45 Have 31% More Genetic Mutations.

Implications for Family Planning

For couples planning a pregnancy, this study reinforces that both partners' ages matter. Men should not assume that their fertility is unaffected by time. If a man is over 45 and planning to have children, it may be worth discussing potential risks with a healthcare provider. The background to this story is set out in John Cooper Clarke on Aging: Poetry, Health, and Touring. A related thread runs through Health: latest articles.

For older men considering fatherhood, genetic counseling and sperm testing could provide useful information. The study doesn't suggest that older men shouldn't have children, but it does highlight the importance of informed decision-making. Earlier coverage in Metabolic Health and Brain Aging: How Poor Metabolism Speeds Decline shows how the argument developed. A closer look at the same subject appears in Testosterone Levels Have Fallen 54% in Men Since 1972, Study Finds.

As research continues to uncover the nuances of male reproductive aging, the conversation around biological clocks is becoming more inclusive. The evidence is clear: sperm also ages, and the genetic mutations accumulate over time. Anyone following the wider picture can start with Exercise Triggers Muscle Cleanup and Reset, Stem Cell Expert Says. The same theme surfaces in Sperm Count Decline: The Truth About Spermageddon and Fertility, which takes a different angle.

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