Age and fertility: what men should know about their chance of a healthy baby

4 min

Most men want to be fathers one day, but research suggests many don’t realise they have a biological clock that affects their chance of a healthy baby.

A survey of 700 Australians by Your Fertility found very few knew that male fertility declines from about the age of 45. And for all the historical talk of a woman’s ‘clock ticking’, only one in three respondents knew that a woman’s fertility starts to decrease at the beginning of her 30s.

So, here’s five things aspiring fathers should know about the impact of age on their fertility:

1. A man’s age affects the chance of conception

We’ve all heard about men in their 80s and 90s fathering children, but it’s rare. Men don’t lose their fertility entirely with age, but their chance of conceiving deteriorates over time in line with the quality of their sperm.

Research shows that across the population, men younger than 40 have a better chance of having a child than older men. This is true for natural pregnancies and for pregnancies conceived through assisted reproductive treatments such as IVF.

A man’s age also affects how long it takes to conceive. One study found that if a 25-year-old woman partners a man who is also younger than 25, it takes an average of five months to get pregnant. If her male partner is older than 40, it takes around two years.

2. A man’s age can increase the chance of miscarriage

It’s long been known that the older a woman is, the higher her chance of miscarriage. But there’s a growing appreciation of the man’s age as a factor too. A team of researchers recently looked at 10 studies estimating the effect of a man’s age on the risk of miscarriage.

Overall, the results showed that the older the father is, the higher the risk of miscarriage. Compared to men aged under 30, men aged 40 to 44 have a 23 per cent higher risk of their partner suffering miscarriage. And for men aged over 44, the risk increased by 43 per cent.

3. Older age increases the chance of problems for the baby

Because of the changes that happen in eggs and sperm as we age, including damage to genetic material, children of older parents have a slightly higher risk of birth defects and genetic abnormalities.

The risk of conditions such as dwarfism, schizophrenia, epilepsy and autism spectrum disorders is marginally higher in children of fathers older than 40 than in those with younger fathers.

A woman’s age also affects the risk. Overall, it’s estimated that the risk of having a baby with a chromosomal abnormality is approximately one in 400 for a woman aged 30 and one in 100 for a woman aged 40.

4. Women’s fertility declines during their 30s

A lot of things can get in the way of feeling ready for a baby, but if men feel inclined to put it off, they should consider their partner’s age. It’s a biological fact that as women age, their potential to have children decreases, although the exact time when this starts to happen can vary among individuals.

Research has shown that women younger than 30 have about a 20 per cent chance of getting pregnant naturally each month. By age 40, the chance of pregnancy is about five per cent each month.

In general:

  • Women are most fertile before the age of 30
  • After 30, women’s fertility starts to decrease
  • After 35, fertility declines more significantly
  • By 40, a woman’s fertility is about half the level it was before she was 30.
5. IVF cannot work miracles

Most respondents to the Your Fertility survey over-estimated the chance of IVF working for a woman in her 40s, suggesting misconceptions about fertility treatment.

IVF can help people with infertility have a family but cannot make up for the natural decline in fertility that happens as women and men get older. That’s why very few women in their 40s achieve pregnancy with IVF using their own eggs. And overall, IVF success rates are lower for women whose partner is aged over 41.

For more evidence-based information about fertility, men, partners and health professionals can visit Your Fertility.

Your Fertility is brought to you by the Fertility Coalition which includes: Victorian Assisted Reproductive Treatment Authority (VARTA), Healthy Male, Jean Hailes for Women’s Health, Global and Women’s Health at Monash University and The Robinson Research Institute at The University of Adelaide.


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