Influence of late-age births on maternal longevity

PurposeTo examine the association between the mother's age at last birth and maternal long-term survival.MethodsData from three national censuses (1972, 1983, and 1995) and national birth and death records (1972–2009) were used to examine the association between age at last birth and mortality while accounting for potential confounders, such as parity. Age-adjusted mortality rates and Cox proportional hazard models were used in the analysis.ResultsA total of 887 women who delivered their last child after 45 years of age were identified from among 178,507 women (1,592,379 person-years). Age-adjusted mortality rates from 55 years of age were highest for childless women (9.2 per 1000) and decreased linearly (P < .001) for parous women with increased age at last birth (5.2 per 1000 for women aged ≥45 years at last birth). In models adjusted for age at first birth and parity, mortality risks were lowest among parous women with late-age births (≥45 years) compared with parous women with their last births before 35 years of age (hazard ratio, 0.58; 95% confidence interval, 0.40–0.86).ConclusionsThis study provides new empirical evidence that late-age births are associated with maternal longevity, although a direct causal relation cannot be established with the information available.