Could your baby’s birth year predict the year you die? The surprising age–life link explained

We looked at the research to find the magic number for when to have kids to increase your chances of a long (albeit noisy and sleep-deprived) life, as well as how having them full stop can boost your health in miraculous ways.

The average age women have babies in 2025

In 2025, more women over 40 had babies than women under 20 for the first time in US history (a trend that has been going on since 2015 in the UK). And the average age for a woman to have her first baby is now hovering around 30 for the first time in the UK, Europe and the USA.

Projections show that this trend for older mothers will continue further, with girls who are turning 18 in 2025 predicted to have just one child per woman by the age of 35 as well as having less children overall – an average of 1.52 children during their life compared to the 1.95 children of their mother’s generation and the 2.04 children of their grandmother’s generation.

The ever-increasing age of women at first birth is undoubtedly having an impact on how many babies are being born, but does that mean population in the UK and US will decline sharply? Potentially not, because science also shows us that these older parents might just live a lot longer than you’d expect…

How the age you have children can help you live longer

We all know that, biologically-speaking, having kids in our 20s (especially from 25 – 30) is considered ideal in terms of being at peak fertility and having less pregnancy and birth complications. After 35, a woman’s ovarian reserve declines sharply and pregnancy risks and fetal anomalies, including gestational diabetes and having a baby with Down’s Syndrome, increases.

However, being older when you have your babies isn’t all bad news for women. In fact, there are some surprising benefits.

Research shows that women who have their last baby after the age of 33 have a longer life expectancy than those who completed their family at an earlier age! And we’re not just talking living a few months longer here.

A study published in Menopause in January 2015 showed that women who had their last baby after the age of 33 doubled their chances of living to 95 years or older compared to women who had their last child by 29!

And another piece of research, The New England Centenarian Study, that has been following and studying centenarians and their families since 1995 took this even further, showing that women who gave birth after 40 were four times more likely to live to 100 years old!

The 2015 study also found that “for each additional year in maternal age at last birth, the odds of exceptional longevity increased by 5%”, and a later 2024 study found that “for each year increase in the age of the birth of the last child, a woman's lifespan increased by 0.06 years (22 days).”

So, is the act of having a baby later the sole reason that mothers live longer?

Unfortunately, it’s a bit more complicated than that, with multiple other factors coming into play. The very fact that a woman can conceive and carry a child later in life suggests that she may possess a gene that slows aging and therefore, even without having children, would always live to an old age.

These older mothers are then believed to pass these slow ageing genes on to their offspring, meaning women born of older mothers are predicted to live even longer and continue the trend.

A 2017 study supported this theory, showing that there was a genetic link between reproductive longevity and slow aging. This is believed to be due to these women possessing chromosomes with a longer telomere length (a protective cap at the end of a chromosome that prevents it from being damaged during cell division).

Other factors that play a part include the fact that women who have their children at an older age tend to have a higher socioeconomic status and are often well-educated, delaying having children to focus on their careers first.

As these women have higher incomes and have benefited from a good education, they tend to have healthier lifestyles with the funds and knowledge to focus on regular exercise and healthy foods – all of which contribute to a longer healthier life. Multiple studies in the US and the UK show that higher earners have a longer life expectancy.

How kids can help boost your immune system

Every new parent dreads the day they send their child to nursery, pre-school or big school for the first time and await the inevitable back-to-back bugs that come home and spread around the house.

While these endless colds, coughs and sick bugs can make you feel like death for those first few years, research actually suggests they could be helping you to live longer!

Researchers Miguel Portela and Paul Schweinzer have come up with the ‘parental co-immunisation hypothesis’ that shows that parents have less risk of dying from infections than non-parents because their immune systems are being refreshed by their child’s infections at a point in their life when their own protection normally starts to decline.

So, the next time your child sneezes in your face, remember to thank them – it could be adding years to your life!

How kids can help protect your brain from ageing

If you have a whole brood of kids and wonder what on earth the constant noise, endless admin, and brain overload is doing to your health, then fear not. Logically you’d think the more kids you have, the more it ages you. But in fact, research shows us that’s not quite the case.

Next time you worry that the mayhem of multiple kids is going to be the death of you, you might want to remember that recent research reveals that the more kids you have, the better it is for your brain.

A January 2025 study of 37,000 adults published in the Proceedings of the Natural Academy of Sciences showed that raising children offers some protection against the effects of aging on parents’ brains, with the effect strengthening with each additional child.

And it’s not just mothers who have given birth who benefit – both mothers and fathers with biological or adopted children were seen to have patterns of brain connectivity that directly oppose typical age-related changes, suggesting it’s the experience of parenting that offers the protection.

The most startling finding though, was that the more children a parent had, the stronger the brain differences appeared to be – showing that having more children helps delay your brain ageing.

How having kids can help reduce your chances of cancer

Cancer is the leading cause of death in the UK and the second most common cause of death globally (after heart disease), so anything you can do to reduce your chances of cancer has to be worth a try.

Along with avoiding smoking and alcohol, wearing sunscreen, eating a healthy diet and being physically active there are some less well-documented ways to reduce your chances, including having kids.

According to research having kids can reduce a mother’s chances of breast cancer, and the more kids you have the more this chance decreases. In fact, one study from 1996 showed that women who have given birth to five or more children have half the breast cancer risk of women who have not given birth, although another study from 2011 shows that having more children could increase the risk of a rarer triple negative breast cancer diagnosis.

However, it’s important to note that while the risk of breast cancer does decrease in women who have given birth, this reduction may only come into play 20 years after the baby is born and in fact, there’s a slight increase in the chances of developing cancer in the years after giving birth.

Another important factor in how children can reduce your cancer risk is in how you feed them. A study from 2022 found that “breastfeeding reduces the risk of breast cancer by 4.3% for every 12 months of breastfeeding, which is in addition to the 7.0% decrease in risk observed for each birth.”

How the number of children you have can help you live longer

Having multiple children appears to protect your brain from ageing as well as reducing your risk of some of the more common types of breast cancer (years after the birth of your last child). But is there a magic number of offspring associated with a parents’ life expectancy?

According to the 2015 study mentioned above you can indeed put a number on it: “Our findings are consistent with those of the Rotterdam Study which noted significantly lower mortality for women who had 2-3 children compared to those who had no children or those who had more than 3 children.”

It’s not just the physical fact of having children that makes you live longer though – having multiple children increases your chances of receiving social support from your children in your old age. Plus, having dependents, even when they’re adults, gives older parents a focus and keeps them more active and mentally engaged too.

So what’s the best age to have your kids if you want to live for longer?

Of course, there’s no one perfect age to have babies that suits every woman. Anyone hoping to have kids needs to consider a multitude of things including fertility, mental and physical readiness, career, finances and support system first.

However, if we simply look at the research to decide which age to have kids to try and ensure you’ll be around to see your grandchildren grow up (and maybe even meet a great-grandchild), there is an “ideal” range to aim for.

Starting with the earliest ideal age for longevity we can see that having children after 25 is best – a study from 2016 shows mothers are 11% more likely to survive into their 90s than women who first gave birth at an earlier age.

Then if you consider the study that shows that having your last child after the age of 33 doubles your chances of making it past 95 years of age, plus the study that shows that giving birth after 40 means you’re four times as likely to live to 100, the “ideal” age for having children in terms of life expectancy moves from your mid 20s up to your 30s.

Finally, we need to take fertility into account and the fact that it drops off significantly after 35, plus the fact that having multiple children (around 2-3) has been shown to help parents live longer.

Considering all these factors, the age range for having babies that gives parents the best chance of living a long life is around 29-34 years of age. And, with figures showing the average age for a woman to have her first baby in England and Wales is now at 30.9 years, we can expect to see plenty of today's new parents making it to their 90s and beyond!