We hear a lot about the health risks associated with women putting off having babies until they're in their 30s or 40s - and for many women with ticking biological clocks who aren't ready to settle down just yet, it can be a pretty depressing state of affairs.

But now a study has revealed that children born to older mothers can actually end up taller, fitter, and better educated than those born to younger women. And it has nothing to do with the mums' age at all - it's all about the rate at which society is advancing.

In fact, it turns out that industrialised society has been improving so quickly that the benefits of being born just a few years later - into a world with better healthcare and education options - can outweigh the biological risks associated with being born to an older mother.

To figure this out, the researchers looked at data from more than 1.5 million men and women in Sweden born between 1960 and 1991, and found that when mothers put off having kids until they were older - even into their 40s - they were more likely to have children who were taller, more physically fit, got better grades in high school, and were more likely to go to university. 

"The benefits associated with being born in a later year outweigh the individual risk factors arising from being born to an older mother," said lead researcher Mikko Myrskylä from the Max Planck Institute in Germany.

"We need to develop a different perspective on advanced maternal age. Expectant parents are typically well aware of the risks associated with late pregnancy, but they are less aware of the positive effects."

The team was particularly interested in comparing the data on siblings born to the same mother. Seeing as siblings share 50 percent of their genes and are usually raised in a similar environment, it allowed the researchers to isolate the effect that being born earlier or later was having on their success in life.

For example, they found that even when siblings were born to the same mother decades apart, on average, the child born when the mother was in her 40s ended up being better educated than the child born when the mum was in her 20s, her 'fertile prime'.

If that sounds surprising, just think of all the social changes that took place between the '70s and '90s.

"Those 20 years make a huge difference," said Myrskylä. "A child born in 1990, for example, had a much higher probability of going to a college or university than somebody born 20 years earlier," a press release explains.

To be clear, the risks of having children later in life are still real - delaying pregnancy comes with an increased risk of Down syndrome, and a higher chance of your baby growing up to develop Alzheimer's disease, hypertension, and diabetes later in life.

But with treatments for those conditions - as well as general healthcare - improving all the time, those risks can be outweighed, the researchers conclude. 

One thing to note is that this study only looked at data in Sweden - an industrialised country that underwent significant change between the '60s and '90s. Nowadays, with climate change breathing down our neck, it's unfortunately no longer a given that the world will be a better place for our children than it is now

But the good thing about this research is that there's awesome news in there for everyone, no matter what your lifestyle choices. Had kids young? That's great! Biology is on your side. Put it off until you were 38? Don't worry, the world you raise them in will (hopefully) be way more advanced, counteracting any health risks.

In other words, you do you, ladies. So let's cut the guilt and focus on making the world a better place for the next generation instead.

The research has been published in Population and Development Review.