Giving birth ages women faster than smoking or obesity, study suggests
Having children adds eleven years to a woman’s biological age and accelerates the ageing process more than smoking or obesity, according to new research.
Scientists at the George Mason University in Virginia measured the lengths of telomeres, the end section of a chromosome associated with longevity, in women with children. The results, published in the journal Human Reproduction, showed that the length of their telomeres were on par with women more than ten years older than them.
“We were surprised to find such a striking result. It is equivalent to around 11 years of accelerated cellular ageing,”said study author Dr Anna Pollack. Women who had five or more children had even shorter telomeres compared to those who had none, and relatively shorter than those who had one, two, three or even four, according to the study.
Shorter telomeres have been linked with a range of chronic health conditions and mortality. Motherhood shortened the telomeres by around 4.2 percent, even greater than that of the impact of smoking or obesity, researchers found.
The study examined data from over 1,900 women between the ages of 20 and 44, who took part in the National Health and Nutrition Examination Survey, 1999-2002, the only survey period which includes measurement of telomere length. Scientists say the results should be interpreted with caution, however, as they were unable to factor-in external influences like stress and fertility status, due to the cross-sectional nature of the study.
Previous research carried out at Simon Fraser University in Canada found the opposite to be true in an analysis of Guatemalan communities. It found that women who give birth to more surviving children exhibited longer telomeres.
Scientists proposed that the women’s social environment may have been a factor in the result, noting that, in these rural communities, mothers who bear numerous children receive more social support from their relatives and friends, which leads to an increase in the amount of metabolic energy that can be allocated to tissue maintenance, thereby slowing down the ageing process.
Sexual intimacy has also been linked to the length of a woman's telomere. A study published in Psychoneuroendocrinology in 2017 found that women who have sex at least once a week displayed longer telomeres. This increased telomere length was not associated with any other relationship factors, according to the research.
“Scientifically, this does fit with what we understand pretty well. We know that having kids is associated with a higher risk of heart disease and diabetes,” Pollack said. However, the team concluded that further research was warranted into the relationship between giving birth and cellular ageing.
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