A recent study conducted by the University of Helsinki and the Minerva Foundation Institute for Medical Research has revealed significant links between women’s reproductive history and both their lifespan and biological aging. The research, which analyzed data from nearly 15,000 participants in the Finnish Twin Cohort, found that women who have large families, those without children, and those who had their first child at a very young age tend to age at a faster rate than their peers.
The findings, published in the journal Nature Communications, indicate that the number of children a woman has, as well as the timing of her pregnancies, can impact her overall health and life expectancy. Women who had between two and three children generally exhibited the longest lifespans, while pregnancies occurring between the ages of 24 and 38 were associated with healthier aging patterns.
Key Findings on Family Size and Aging
Among the surprising outcomes of the study, researchers observed that women with more than four children showed a correlation with shorter lifespans and accelerated biological aging. This aligns with the life history theory in evolutionary biology, which suggests that organisms have limited resources such as time and energy. According to doctoral researcher Mikaela Hukkanen, “When a large amount of energy is invested in reproduction, it is taken away from bodily maintenance and repair mechanisms, which could reduce lifespan.”
Interestingly, childless women were found to age biologically faster than those with a small number of children. This anomaly may be attributed to unmeasured lifestyle or health-related factors that could not be fully accounted for during the analysis. The researchers caution that these findings are applicable only at the population level and do not imply a cause-effect relationship for individuals.
Dr. Miina Ollikainen, the lead on the study, emphasized that the results should not dictate personal reproductive choices. Family sizes have decreased, and the age at first childbirth has risen since the period covered by this study, which began with a questionnaire in 1975.
Biological Aging Measured Through Epigenetics
Another critical aspect of the study was the measurement of biological aging through epigenetic clocks derived from blood samples of over 1,000 participants. These clocks aim to assess the gradual deterioration of cells and tissues, providing insights into aging that can be detected years before death. The results corroborated earlier mortality data, revealing that women with either many children or none at all were biologically older than their chronological age.
Dr. Ollikainen stated, “A person who is biologically older than their calendar age is at a higher risk of death.” The study’s analysis also indicated that early childbearing was linked to biological aging, suggesting an evolutionary trade-off where natural selection may favor earlier reproduction, despite potential health costs associated with aging.
The research underscores the lasting impact of reproductive choices on biological health, but researchers continue to highlight the need for further investigation into the complex interplay of factors influencing lifespan and aging.
For more detailed insights, the full study can be accessed in Nature Communications under the citation: Hukkanen, M., et al. (2026). Epigenetic aging and lifespan reflect reproductive history in the Finnish Twin Cohort. doi: 10.1038/s41467-025-67798-y.
