Pregnancies that follow one another in quick succession could accelerate the mother’s biological ageing, according to a study

This review article puts forward an intriguing and plausible evolutionary hypothesis: that during pregnancy, a significant endocrine, immune and metabolic remodelling of the maternal organism takes place, with processes associated with biological ageing that appear to accelerate throughout gestation but are partially reversed after birth. The review combines findings from human cohorts and various measurement platforms (epigenetic clocks, telomere length and clinical markers) to propose that a subsequent pregnancy, before full recovery from the first, may preserve the deficit and accumulate changes between pregnancies. Of course, it is critically important to distinguish between changes in the markers we use to estimate biological age and actual permanent ageing of the body. This hypothesis opens up interesting possibilities, but it has not yet been demonstrated that short pregnancies are responsible for the apparent effects of irreversibly aged cells, nor whether changes in structure necessarily lead to clinically significant long-term outcomes.

One limitation is that this is a review and constructs the conceptual framework based on previous studies—primarily observational ones—rather than an experimental study demonstrating causality. Although associations have been observed between intervals between pregnancies and certain obstetric and perinatal outcomes, it cannot be concluded that a short interval, on its own, causes an increase in biological age. Postpartum recovery and the biomarkers examined may be influenced by maternal age, body mass index, pre-existing conditions (particularly gestational diabetes), nutritional status, stress, the duration of sleep deprivation during breastfeeding, and socio-economic conditions.

Furthermore, epigenetic clocks and other indicators of biological age are also indirect measures. The differences may represent physiological or inflammatory changes, or variations in cellular composition during pregnancy that do not constitute irreversible damage. There is a lack of measurements that account for the time required for full recovery and whether incomplete recovery persists decades later, but this is acknowledged in the article itself.

They therefore provide a promising framework for guiding future research, but their results must be interpreted with caution. It is not a message that should be conveyed to women—that they will age more rapidly if pregnancies are too closely spaced—especially given our low birth rate. The key question is whether, in longitudinal studies, changes in these biomarkers would be sustained; which modifiers affect recovery and shape long-term maternal health; and what the actual implications of these markers are for mothers.  

This timely review by Albright and Poganik published in Trends in Endocrinology & Metabolism synthesizes evidence from multiple longitudinal cohorts and biological aging measures to propose a novel, testable hypothesis: that long-term maternal biological aging trajectories may be influenced by the time available for postpartum recovery between pregnancies, rather than by the number of pregnancies.

Biological aging refers to the progressive accumulation of molecular, cellular, and physiological changes that impair bodily function and increase vulnerability to age-related diseases and mortality. Most commonly, this is measured via epigenetic age clocks, which are mathematical models based on patterns in DNA methylation. The review builds on a growing body of evidence showing that pregnancy is associated with accelerated epigenetic aging, followed by partial reversal postpartum. Specifically, interpregnancy interval, defined as the time between delivery and subsequent conception, is proposed as a missing variable to elucidate the biological burden of pregnancy on aging outcomes.

This article’s principal contribution is integrating these findings with epidemiological evidence on pregnancy spacing, parity, and maternal health. However, the evidence supporting the proposed recovery-window hypothesis remains preliminary. Although longitudinal findings suggest that subsequent pregnancies may interrupt biological age recovery, studies have not established that shorter interpregnancy intervals cause persistent acceleration of biological aging or increase long-term mortality through this mechanism. Most existing research is largely observational, some key studies have relatively small samples, and findings may be influenced by maternal age, socioeconomic circumstances, breastfeeding, body mass index, psychosocial stress, and other factors.

There is an important distinction between the relatively well-supported observation that markers of biological age change during pregnancy and postpartum, versus the still-untested hypothesis that insufficient recovery between pregnancies causes cumulative, lasting biological aging. Importantly, epigenetic clocks and other biological age measures are indirect biomarkers, developed in nonpregnant populations, thus, pregnancy-related changes may reflect normal, adaptive physiological remodeling rather than accumulated cellular damage or irreversible aging. The findings therefore should not be reported as demonstrating that pregnancy permanently ages women, that closely spaced pregnancies necessarily accelerate aging, or that a particular interpregnancy interval prevents biological aging. Rather, this review provides a compelling framework for future longitudinal research examining whether postpartum recovery trajectories predict subsequent health and whether modifiable factors can improve maternal recovery. 

Is this a high-quality study? Are its conclusions supported by robust evidence?

I think this is a thoughtful paper that makes a useful contribution. Pregnancy brings about dramatic changes to a woman’s body. Many resolve after pregnancy, but others may persist, and we still have a lot to learn about what they mean for women's health later in life. The authors suggest that recovery between pregnancies could be an important part of the story. That is a plausible idea, but we still do not yet have strong evidence to say that if that is true or not.

How does this research fit into the existing body of evidence?

The research on pregnancy and biological aging is growing quickly, and the findings have sometimes been mixed. The “recovery period hypothesis” does a good job of bringing that literature together. This framework also gives us a useful way to think about those findings and raises questions that future studies can test.


Are there any important limitations that should be highlighted?

We still do not know if the time between births is a reliable measure of recovery. One of the challenges is that many factors influence both pregnancy spacing and maternal health, making their effects difficult to separate. Breastfeeding, for example, may support some aspects of recovery while also delaying the next pregnancy. Health, stress, fertility, access to contraception, and social and economic support could also shape both. Teasing these social and biological factors apart remains a major challenge to understanding whether the time between births affects women’s long-term health.

What should journalists bear in mind when reporting on the findings?

I would emphasize that this is a hypothesis. We cannot conclude from this paper that closely spaced pregnancies accelerate aging, or say how much time between pregnancies would allow for “enough” recovery.

We also need to be careful about what we mean by biological aging during pregnancy. Most of these measures were developed in people who were not pregnant. When they change during pregnancy, we do not yet know how much reflects lasting costs and how much reflects the body adapting to pregnancy. That distinction matters before we describe those changes as evidence of accelerated aging.