Number of children linked to lifespan and biological aging, study finds
Mar 7th 2026
A large twin study led by the University of Helsinki finds women with no children or very many children tend to show faster biological aging and higher mortality, while those with two to three children and mid adult childbirth ages show the lowest risk; the results show population level associations and do not prove causation.
- Researchers analyzed 14,836 Finnish twin women, with 1,054 assessed for biological aging markers, to reduce genetic confounding.
- Women with no children and those in the highest parity group (average 6.8 children) showed faster biological aging and higher mortality risk.
- The lowest biological aging and mortality risk occurred in women with about two to three children and childbearing roughly between ages 24 and 38.
- Earlier childbirth was associated with faster biological aging, but this link largely weakened after adjusting for factors like alcohol use and BMI.
- The findings are associations, not proof of cause and effect, and the authors warn individuals not to change family plans based on this study.
- Authors say the results are consistent with evolutionary theories about trade offs between reproduction and bodily maintenance, but unmeasured factors may explain some links.