Women really are aged by motherhood, scientists find

Pregnancy accelerates biological ageing – each baby makes women grow older by up to 2.8 months

EXASPERATED mothers often warn that their children “will be the death of them”, and a new study suggests that there may be some truth in the admonishment.

Pregnancy accelerates biological ageing with each baby causing women to grow older by up to 2.8 months, scientists have discovered.

Carrying a child is known to have long -term health impacts, but previous studies have found they are largely beneficial, such as lowering the risk of cancer and dementia. Now new research by Columbia University in New York has shown that pregnancy takes such a toll on the body that it causes a woman to age internally.

The research, which was carried out on 1,735 young people in the Philippines, looked at alterations to DNA to calculate the biological age of mothers compared with their actual age.

Throughout life, as a person ages, small molecules get added to their DNA, giving 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 team found that men were not impacted in the same way, with their DNA unaffected by fatherhood. This implies that it is something about pregnancy, or breastfeeding specifically, that accelerates biological ageing, the researchers said.

“Our findings suggest that pregnancy speeds up biological ageing and that these effects are apparent in young, high-fertility women,” said Dr Calen Ryan, the lead author of the study and an associate research scientist at the Columbia Aging Center. “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 reported having been pregnant appeared biologically older than those who had never been pregnant. Women who had been pregnant more often were biologically older again than those who reported fewer pregnancies. The relationship between pregnancy history and biological age remained even after taking into account other factors tied to biological ageing, such as socioeconomic status, smoking, and genetic variation.

Dr Ryan added: “We still have a lot to learn about the role of pregnancy and other aspects of reproduction in the ageing process.”

The research was published in the journal PNAS.