This study seems a bit counterintuitive as kids sometimes can make you feel pretty old, but this new study at the Simon Fraser University suggests that the number of children born to a woman influences the rate at which her body ages.
Great news for my own mother it seems as I am the oldest of 9…
From the press release:
The study led by health sciences professor Pablo Nepomnaschy and postdoctoral researcher Cindy Barha found that women who give birth to more surviving children exhibited longer telomeres. Telomeres are the protective tips found at the end of each DNA strand and are indicative of cellular aging. Longer telomeres are integral to cell replication and are associated with longevity.
The study assessed the number of children born to 75 women from two neighbouring indigenous rural Guatemalan communities, and their telomere lengths. The participants’ telomere lengths were measured at two time points 13 years apart, through salivary specimens and buccal swabs. This is the first study to examine the direct association between the number of children and telomere shortening in humans over time.
According to Nepomnaschy, the study findings contradicts life history theory which predicts that producing a higher number of offspring accelerates the pace of biological aging. “The slower pace of telomere shortening found in the study participants who have more children however, may be attributed to the dramatic increase in estrogen, a hormone produced during pregnancy,” says Nepomnaschy who also spearheads the Maternal and Child Health Laboratory at the SFU Faculty of Health Sciences. “Estrogen functions as a potent antioxidant that protects cells against telomere shortening.”
The social environment that the study participants live in may also influence the relationship between their reproductive efforts and the pace of aging. “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,” explains Nepomnaschy. “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.”
Abstract of the study:
Life history theory (LHT) predicts a trade-off between reproductive effort and the pace of biological aging. Energy invested in reproduction is not available for tissue maintenance, thus having more offspring is expected to lead to accelerated senescence. Studies conducted in a variety of non-human species are consistent with this LHT prediction. Here we investigate the relationship between the number of surviving children born to a woman and telomere length (TL, a marker of cellular aging) over 13 years in a group of 75 Kaqchikel Mayan women. Contrary to LHT’s prediction, women who had fewer children exhibited shorter TLs than those who had more children (p = 0.045) after controlling for TL at the onset of the 13-year study period. An “ultimate” explanation for this apparently protective effect of having more children may lay with human’s cooperative-breeding strategy. In a number of socio-economic and cultural contexts, having more chilren appears to be linked to an increase in social support for mothers (e.g., allomaternal care). Higher social support, has been argued to reduce the costs of further reproduction. Lower reproductive costs may make more metabolic energy available for tissue maintenance, resulting in a slower pace of cellular aging. At a “proximate” level, mechanisms involved may include the actions of the gonadal steroid estradiol, which increases dramatically during pregnancy. Estradiol is known to protect TL from the effects of oxidative stress as well as increase telomerase activity, an enzyme that maintains TL. Future research should explore the potential role of social support as well as that of estradiol and other potential biological pathways in the trade-offs between reproductive effort and the pace of cellular aging within and among human as well as in non-human populations.