Short gaps between pregnancies may accelerate biological aging in mothers

The study of biological aging, how our cells, tissues, and organs change over time, independent of how many years have passed, is a growing area of research that aims to help scientists understand the root causes of chronic illnesses and find ways to enhance longevity. A review article publishing in the Cell Press journal Trends in Endocrinology & Metabolism on October 22 discusses the connections between pregnancy and biological aging. The authors hypothesize that when pregnancies occur too closely together, the body may not have enough time to recover-causing changes related to biological aging to accumulate. They hope that studying the biological changes that occur during pregnancy can help improve maternal health. 

Our previous research has found that biological age transiently rises during pregnancy, peaking around the third trimester or at the time of delivery. If we accept the idea that these short-term changes in biological age occur, the question is how we can relate those changes to the overall trajectory of aging over the course of a lifetime." 

Jesse Poganik, corresponding author, Harvard Medical School

In this article, the authors propose that the recovery time between pregnancies may ultimately affect a mother's long-term health. Repeated pregnancies with short intervals in between could potentially prevent complete recovery, allowing some changes to accumulate over successive pregnancies. 

"It's possible that this could change the overall trajectory of aging," Poganik says, but he adds that these changes don't necessarily equate with biological damage. "We know that some level of parity, or carrying a pregnancy to term, is actually beneficial to a person's lifespan." 

The World Health Organization currently recommends waiting a minimum of 24 months after a live birth before conceiving another child, as a way to reduce health risks for both mother and baby. But Poganik explains that to make specific recommendations based on biological aging rather than pregnancy outcomes, additional research would be needed to measure biological age across multiple pregnancies and then follow the mothers for decades afterwards. 

Beyond the study of long-term aging, this research also has implications for improving maternal health during and after pregnancy. "What motivates me on a more near-term basis is addressing current clinical challenges, including the huge maternal mortality crisis in the United States compared with other industrialized countries," Poganik says. "Any insights we can gain that can improve the health of mothers makes this a worthwhile research endeavor." 

In addition to methylation patterns in blood, many other tools can contribute to the study of biological aging, both in pregnant people and in wider populations. These include brain-imaging studies and data from wearable devices. 

"There's a lot of excitement about using biological age-assessment tools to guide individual health on a preventative and personalized level," Poganik says. "Studying changes during pregnancy is just one way to gain a more fundamental understanding of aging more broadly." 

This work was supported by funding from the Hevolution Foundation, the Brigham and Women's Hospital Connors Center WHISPR (Women's Health Interdisciplinary Stress Program of Research) Award, and the Gretchen S. Fish Fund for Women's Health and Stress Research.