Birth Effects

Chromosomes stained to show their telomere endcaps

U.S. Department of Energy Human Genome Program

Telomeres, the DNA structures that serve as protective caps at the ends of our chromosomes, play a role in how chromosomes replicate and how cells divide. It has long been known that telomeres gradually grow shorter as we age. A new study suggests that giving birth may also shorten the telomeres of reproductive-age women.

Researchers led by Anna Pollack, an assistant professor of global and community health at George Mason University in Fairfax, VA, used data from the National Health and Nutrition Examination Survey, conducted by the Centers for Disease Control and Prevention, to compare telomere length in a sample size of 1505 women, who had reproduced, with 444 similarly-aged women, who had not. The data showed the telomeres of the child-bearing women were significantly shorter on average than those in childless women.

The amount of telomere shortening in women who had given birth equated to approximately eleven years of chromosomal aging. Because shortened telomeres are associated with higher risks for cancers and chronic conditions such as type 2 diabetes, cardiovascular disease, and atherosclerosis, this may leave mothers more prone to severe illness and death. In fact, the telomere shortening in mothers proved greater than telomere shortening reported in people who are obese or who smoke.

Pollack emphasizes that more research will be needed to ferret out the apparent links between motherhood and telomere-correlated risk of disease. “It is speculative at this point to attempt to attribute a biologic basis for our findings,” she notes, “but increased stress or the lack of sleep that mothers deal with compared to nulliparous [non-child-bearing] women offer plausible explanations that could underlie our findings."

A key follow-up study would be to assess telomeres among men with and without kids, or in biological versus adoptive parents. Another way to tease apart cause and effect would be to measure telomere length in women before any pregnancies, and then again later in life at different points of parenthood. With such further research, mothers could know for sure if their children are really taking years off their life, or if it only just feels that way. (Human Reproduction)