Mothers with several children saw their cellular age increase by half a year to two years each time they had a baby. Picture: Pixabay

London - There’s many a mother who’ll say that the stresses of parenthood have aged them. And now a study has proved them right.

For researchers found that women’s ageing is accelerated by up to two years every time they give birth.

It means the more children a woman has, the shorter her life expectancy may be. The study, on more than 3 200 women aged 20 to 22 in the Philippines, found each birth has a damaging effect at the cellular level.

Mothers with several children saw their cellular age increase by half a year to two years each time they had a baby, the researchers Northwestern University, Illinois, found. They looked at two markers of cellular ageing - telomere length and epigenetic age - both of which they said ‘independently predict mortality’.

Lead author Calen Ryan said: "Both [markers] appeared 'older' in women who had more pregnancies in their reproductive histories. Even after accounting for other factors that affect cellular aging, the number of pregnancies still came out on top." 

The team said the cellular changes during pregnancy may be related to adaptive changes in the mother’s immune system

They are now carrying out a follow-up study on the women, who had their first measurements taken in 2005, to see if their cells still appear older in later life. The study was published in Scientific Reports.