The researchers suggest the more children a mother has, the slower she may age.
In the journal PLOS One, researchers reveal that women who had more children had longer telomeres than women who had fewer children.
Telomeres are caps at the end of each DNA strand that protect our chromosomes - thread-like structures that contain all our genetic information - from damage.
Each time a cell replicates, telomeres become shorter. They eventually become so short that they stop protecting chromosomes, leaving them vulnerable to damage, which in turn causes our cells to age and stop functioning effectively.
Previously, animal studies have supported the "life history theory," suggesting that higher reproductive behavior is associated with accelerated biological aging.
However, this latest study, led by Prof. Pablo Nepomnaschy and Cindy Barha - both of Simon Fraser University in Canada - contradicts this theory.
Each additional child linked to an increase in telomere length
The team enrolled 75 Kaqchikel Mayan women from two neighboring communities in the southwest highlands of Guatemala, assessing how many children the women gave birth to between 2000-2013.
At the beginning of the 13-year study period, the women's telomere length was measured from saliva samples. Telomere length was measured again at study end, but through a buccal swab.
The researchers found that women who had a higher number of surviving offspring over the course of 13 years had longer telomeres than those who gave birth to fewer surviving children; each additional child born was linked to 0.059 more telomere units.
These results remained after accounting for potential influential factors, including women's age, their age at first birth, their age in 2013, lifestyle habits and family income.
Commenting on their findings, the researchers say:
"Our analyses show that increased offspring number across 13 years of observation attenuated telomere shortening, suggesting that, in our study population, having more children may slow the pace of cellular aging."
Increased estrogen production in pregnancy may explain findings
Prof. Nepomnaschy hypothesizes that their findings may be explained by an increase in the hormone estrogen that arises during pregnancy. "Estrogen functions as a potent antioxidant that protects cells against telomere shortening," he explains.
Furthermore, Prof. Nepomnaschy says social environment may play a role in the association between the number of children a woman has and her pace of aging, noting that the women included in this study who had multiple children had greater social support from family and friends.
"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," he adds.
The team concludes that future studies should investigate the association between reproductive frequency and biological aging in women of different ethnicities and social backgrounds.
Last year, Medical News Today reported on a study in which researchers detailed a possible way to increase the length of human telomeres, paving the way to new treatments for numerous genetic and age-related diseases.