The period after childbirth may play an important role in maternal biological aging and long-term health, according to a review by Mass General Brigham researchers. The study proposes that the time between pregnancies could influence how fully the body recovers from pregnancy-related changes.
Research has linked having more children with an increased risk of heart disease and shorter lifespan in some populations, although findings have been inconsistent. Meanwhile, studies using biological age measurements suggest that pregnancy can temporarily increase biological age, which may partially return towards baseline during postpartum recovery.
Biological age reflects the condition of the body rather than simply the number of years a person has lived. In a paper published in Trends in Endocrinology & Metabolism, researchers propose that the duration of postpartum recovery may help explain differences in long-term health outcomes among women who have multiple pregnancies.
The paper, titled The Postpartum Recovery Window as a Determinant of Maternal Aging, was led by Stephen Albright, formerly of Mass General Brigham, with Jesse Poganik, PhD, of its Division of Genetics, Department of Medicine, as senior author.
The researchers call their proposed explanation the “recovery period hypothesis.” It suggests that if another pregnancy begins before the body has sufficiently recovered from the previous one, the physiological demands may accumulate across pregnancies.
Evidence Points to Changes Across Multiple Biological Measures
As this was a review rather than a new experimental study, the researchers examined published evidence from several fields. They considered studies measuring biological age through wearable-device data, brain imaging, routine blood tests and epigenetic clocks, which assess chemical modifications to DNA.
The review found consistent evidence across studies from Europe, the United States and the Philippines that biological age can rise temporarily during pregnancy and partially recover afterward. The recovery period may last several months to a year or longer, with factors such as pre-pregnancy weight, breastfeeding and potentially sleep influencing the process.
Early evidence also suggests that becoming pregnant again during this recovery window could interrupt the return towards baseline biological age. However, the authors emphasise that the connection between pregnancy spacing, biological aging and later-life health remains a hypothesis that requires direct testing.
Implications for Postpartum Care and Pregnancy Spacing
The researchers argue that postpartum care should be considered not only in terms of immediate recovery from childbirth but also as a potential contributor to long-term maternal health. Supporting sleep, breastfeeding where appropriate and metabolic health could help women recover from the physical demands of pregnancy.
If future research confirms the hypothesis, pregnancy-spacing guidance might eventually consider maternal long-term health alongside birth outcomes. Biological age measurements could also potentially help personalise such guidance.
However, the review does not change existing medical recommendations. The authors note that the World Health Organization has recommended waiting at least two years between pregnancies since 2005.
Further Research Needed to Test the Hypothesis
The team plans to investigate the hypothesis through longitudinal studies that follow women before, during and after pregnancy, repeatedly measuring biological age and recording the intervals between pregnancies.
Researchers are also examining biological aging in individual organs and cell types, rather than relying only on a single whole-body measure. This could help establish whether different organ systems recover at different rates and distinguish potentially harmful changes from healthy adaptations to pregnancy.
In addition, the team plans to analyse existing datasets connecting reproductive histories with long-term health outcomes to determine whether pregnancy spacing helps explain differences between populations.
The authors stress that studies following women for decades beyond their childbearing years will be necessary to establish whether the postpartum recovery window has a lasting effect on maternal health.
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