Number of Live Births Linked to Biologic Aging, Mortality Risk

THURSDAY, Jan. 15, 2026 (HealthDay News) -- The number of live births and timing of pregnancies are associated with women's biologic aging and mortality risk, according to a study published online Jan. 8 in Nature Communications.Mikaela Hukkanen, from the University of Helsinki in Finland, and colleagues examined the relationship between reproductive history and biologic aging and survival within the Finnish Twin Cohort. The association between reproductive trajectories and survival was assessed in 14,836 women. Biological aging was assessed in a subset of 1,054 participants using the PCGrimAge algorithm, trained to predict biologic aging and mortality risk from DNA methylation.The researchers identified six distinct reproductive trajectories, which differed according to the timing and number of childbearing events. Accelerated aging and elevated mortality risk were seen for women with the most live births throughout their lives and nulliparous women (hazard ratios, 1.37 for nulliparous women and 1.22 for women with five or more live births) compared with women with three live births (used as a reference). Women with 2 to 2.4 live births had the slowest aging and longest lifespan on average."From an evolutionary biology perspective, organisms have limited resources such as time and energy. When a large amount of energy is invested in reproduction, it is taken away from bodily maintenance and repair mechanisms, which could reduce lifespan," Hukkanen said in a statement.Abstract/Full Text.Sign up for our weekly HealthDay newsletter