A new study has found that pregnancy accelerates biological ageing, with each baby causing women to grow older by up to 2.8 months.
It is well understood that pregnancy can have long-term health impacts, however, previous research has shown these to be largely beneficial, such as lowering the risk of cancer or dementia. Now, fresh research conducted by Columbia University in New York has shown that carrying a baby exerts such a toll on the body that it causes a woman to age internally.
The study, which was carried out on 1,735 young people in the Philippines, examined alterations to DNA to calculate the biological age of mothers compared with their actual age.
At the start of the study, in 2005, all the participants were of the age group 20-25. They all provided their blood samples and answered a few questions on their reproductive and sexual history, including questions like how many times they had been pregnant and whether or not those pregnancies resulted in live births.
Throughout the lifespan, as a person ages, small molecules are accreted to their DNA, providing updated instructions about how to function. These ‘tags’ accumulate at a steady rate and can be used as a kind of clock that reveals age.
Each additional pregnancy was associated with between 2.4 and 2.8 months of accelerated biological ageing.
The research team found that men were not impacted in the same way, with their DNA unaffected by fatherhood, implying that it is something about pregnancy or breastfeeding specifically which speeds up biological ageing, the researchers said.
What the Pregnancy-Ageing Study Tells Us
“Our findings suggest that pregnancy speeds up biological ageing and that these effects are apparent in young, high-fertility women,” Dr Calen Ryan, lead author of the study and associate research scientist in the Columbia Aging Center told the Telegraph.
“Our results are also the first to follow the same women through time, linking changes in each woman’s pregnancy number to changes in her biological age.
“Ultimately I think our findings highlight the potential long-term impacts of pregnancy on women’s health, and the importance of taking care of new parents, especially young mothers.”
The bodies of women who stated they had been pregnant appeared biologically older than women who had never carried a baby. Women who had been pregnant more often were biologically older than those who reported fewer pregnancies.
Even taking into account other factors linked with biological ageing, such as socioeconomic status, smoking and genetic variation, the relationship between pregnancy history and biological age remained.
Dr Ryan added, “We still have a lot to learn about the role of pregnancy and other aspects of reproduction in the ageing process. We also do not know the extent to which accelerated epigenetic ageing in these particular individuals will manifest as poor health or mortality decades later in life.”
In 2023, a study which employed the UK Biobank found that genes which encourage people to have more children also push them towards an early death.