Women who have given birth seem to have hallmarks of faster biological ageing than those that don鈥檛 鈥� and the difference is equivalent to around 11 years.
That鈥檚 what and her colleagues at George Mason University, Virginia, found when they looked at one measure of biological ageing. The team looked at the length of telomeres 鈥� chunks of DNA that cap the ends of chromosomes. These shorten with each cell division, and shrunken telomeres have been associated with a shorter lifespan, as well as a host of chronic diseases such as heart disease and cancer.
Pollack and her colleagues looked at telomere lengths in blood samples taken between 1999 and 2000 from 1,954 women from across the US. They were all aged between 20 and 44 at the time.
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They found that women who had given birth had telomeres that were on average 4.2 per cent shorter than those who had not had children, even after accounting for factors like age, socioeconomic status and body mass index. 鈥淚t is equivalent to around 11 years of accelerated cellular ageing,鈥� says Pollack.
Unclear cause
The size of the telomere shortening is bigger than that seen in studies of smoking or obesity, says Pollack. 鈥淲e were surprised to find such a striking result.鈥�
It鈥檚 unclear whether this is caused by pregnancy, childbirth, or the experience of raising children. Women who have been pregnant seem to have a degree of protection from some cancers, including breast and uterine cancer, but are more at risk of heart disease and diabetes, thanks to hormonal changes.
The finding contrasts with a , which found that women who had more children had longer telomeres. Pollack wonders if the stress of raising a child 鈥� particularly if given little support 鈥� may play a role. The US is one of the only countries in the world without mandatory maternity leave, so it鈥檚 possible that this takes its toll on the telomeres, suggests Pollack.
No need for alarm
But until we understand the link between motherhood and telomeres, we should be careful about drawing conclusions, says Pollack. 鈥淲e鈥檙e not saying 鈥榙on鈥檛 have children鈥�.鈥�
, at Newcastle University, UK, suggests that the altered telomere length may only really reflect a difference of around 3 years of biological ageing, not 11. 鈥淚t鈥檚 like adding three more drops to a teaspoon,鈥� she says.
And whether the accelerated ageing has an effect on a woman鈥檚 health will depend on a range of other factors, says , at the University of New South Wales in Australia.
Human Reproduction
