If you've ever looked in the mirror at your extra "wisdom highlights" and "smile lines" and thought "Gee, I've aged since becoming a mum", then you're not alone. You're also not wrong.
According to new research published in Scientific Reports, having multiple pregnancies might make women's cells age more quickly, increasing a mama's "biological age".
As part of the study, researchers examined two different markers of cellular ageing - telomere length and epigenetic age - in hundreds of young women in the Philippines. Telomores are found at both ends of each chromosome and protect against chromosomal DNA damage. They get shorter as we age.
The team found that cellular aging sped up between six months and two years for each additional baby. Yep, they're lucky they're cute.
"Telomere length and epigenetic age are cellular markers that independently predict mortality, and both appeared 'older' in women who had more pregnancies in their reproductive histories," said lead author Calan Ryan.
But it wasn't all bad news. Interestingly, pregnant women actually had "younger" looking cells than the researchers predicted. Pregnancy glow, anyone?
"Paradoxically, even though a woman's biological age was higher with each child that she had, if a woman was pregnant when the measurements were taken, her epigenetic age, and to a lesser extent her telomeres, looked 'younger' than predicted for her chronological age," said co-author Christopher Kuzawa. "It's an interesting situation in which pregnancy makes someone look temporarily 'young,' but there appears to be some lasting, cumulative relationship between the number of pregnancies and more accelerated biological age."
If you're wondering whether or not our poor old cells can "recover" and return to what the researchers term more "age-typical" levels, well, the jury is still out. "We also do not know whether these changes will actually lead to less favourable long-term health outcomes," Kuzawa says.
They're questions the team are now exploring as part of a follow-up study of the same women, 13 years after the original research.
"We want to see if we can replicate these findings longitudinally and if cells still look older later in life," Ryan said. "We still have a lot of questions to address that we hope will help us understand how factors like socioeconomic status and diet might contribute to costs of reproduction in women."
It's not the first time science has told us that our kids (bless them) make us older.
Earlier this year, another study published in Human Reproduction found that motherhood ages you faster than smoking or being overweight. Results indicated that women with kids had telomeres that were 4.2 per cent shorter on average than those without. "It is equivalent to around 11 years of accelerated cellular aging," lead reseacher Anna Pollack said at the time.
But before you swear off having any more children, take heart: not all studies return such negative findings. In 2017, research published in PLOS One found that women who had more children had longer telomeres than those who had fewer children. And their explanation for the findings is one we can get behind.
"The women we followed over the course of the study were from natural fertility populations where mothers who bear numerous children receive more social support from their relatives and friends," they wrote at the time. "Greater support leads to an increase in the amount of metabolic energy that can be allocated to tissue maintenance, thereby slowing down the process of aging."
In other words, it takes a village to raise a child - and maybe keep the wrinkles away, too.