Childbearing Imprints Mothers’ Biological Age

A large Finnish twin study (15,000 women followed 1975–2020) reports a U‑shaped relationship between parity/timing and mothers’ biological ageing: having two–three children with births between ~24–38 years associates with slower biological ageing, while childlessness or high parity (4+) associates with accelerated biological ageing even after adjusting for smoking, alcohol, BMI and education. The paper appears in Nature Communications and uses longitudinal twin data to control for familial confounding. — If robust, this finding matters for reproductive, health‑care and demographic policy: it reframes family‑planning debates as not only socioeconomic but also as life‑course health inputs with implications for ageing, long‑term care demand, and gendered health inequality.