February 13, 2026
Yes, men have a biological clock too. But it’s not just age that affects male fertility
How fertile men stay is affected by age as well as a mix of lifestyle, environment and health factors.
When we talk about ticking, it usually means the pressure women feel to fall pregnant before a certain age. It’s linked to the decline in eggs (ova) and fertility as females age.
But sperm numbers and fertility similarly decline with age in men. When a heterosexual couple experiences fertility issues, it’s . Yet the is usually tested first.
But this is changing. New for Australian GPs recommend the male and female partner undergo investigations at the same time.
A growing body of research highlights the role of men in infertility and how a man’s age and health matters when trying to conceive. Let’s look at the evidence.
Semen and sperm health decline with age
Sperm are produced in the testes continuously from , but sperm count (the average number of sperm in an ejaculate) starts to decline when a man is in his early twenties. Men have average sperm counts close to or below the threshold .
But it’s not just the number of sperm that matters.
Sperm need to be alive, have good (movement or “swimming ability”) and be the correct to reach and fertilise an egg in the female reproductive tract.
An adequate volume of (sperm and seminal fluid together) is also necessary because this provides nourishment to sperm.
, the number of sperm with good motility and correct shape, and semen volume decline, while the number of dead sperm increases. The biggest changes generally occur from .
The age-dependent decline in . In studies of more than 2,000 couples, one study showed men older than 45 took than men younger than 25. Another study found the chance of falling pregnant within a year was .
Genetic damage and miscarriage risk increase with age
Though a sperm might have reached and fertilised an egg, if it contains genetic damage, this can also affect fertility or the baby.
As men age, their sperm accumulate more genetic damage, including damage to DNA and (coils of DNA that carry genes). This is because sperm stem cells replicate . Each time a cell replicates, there is a risk of genetic damage.
can stop the embryo developing and result in miscarriage. This is linked to in men older than 40 compared to those aged 25–29.
New have shown also . These can cause and such as and .
Beyond ageing and sperm’s biological clock
Several environmental and lifestyle factors also affect semen and sperm measures, and .
(too many damaging chemicals and not enough antioxidants) disrupts sperm production and increases sperm DNA damage, and is to male infertility.
Oxidative stress is increased by environmental toxins such as pollution, , and some .
Oxidative stress also increases with certain lifestyle factors, including , too much , .
Male infertility can also be due to such as erectile dysfunction, or issues with the male reproductive tract or blood vessels.
A (dilation of the veins that drain the testes) is one of the of male infertility, and treatable.
One or two in 100 men with infertility will , which means their semen does not contain sperm.
However, for of male infertility, the cause is not known.
The new guidelines
The World Health Organization of addressing infertility in everyone, regardless of sex or gender.
Australia’s support this by recommending infertility is investigated in both partners in heterosexual couples. For the male, this includes examination of the penis, scrotum and testes, and semen and blood analyses.
For the in Australia with fertility problems, this will help them find answers and sooner.
Staying healthy for fertility
If you’re looking to conceive, age is a consideration but not the only factor.
For optimal , you can focus on:
- eating a healthy diet with
- not smoking
- reducing alcohol
- maintaining a healthy weight
- exercising
- avoiding
- avoiding excessive exposure to environmental toxins and pollutants.
Reducing unnecessary stress or pressure around falling pregnant is also important. In Australia, pregnancies are normal and most babies are healthy, regardless of the age of the parents.
, Associate Professor of Medical Sciences,
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