Birth characteristics and subsequent risks of maternal cardiovascular disease: effects of gestational age and fetal growth.

BACKGROUND: Prior studies showing an inverse relationship between low birth weight in offspring and maternal risks of cardiovascular diseases (CVD) are limited by lack of information on gestational age and/or insufficient adjustment for confounders.

METHODS AND RESULTS: In a nationwide Swedish study, we included information on 923 686 women and their first singleton births between 1983 and 2005. Cox proportional hazards models were used to study associations between gestational length, fetal growth, and maternal incident hospitalization or death from CVD (coronary heart disease, cerebrovascular events, and heart failure). Multivariable adjusted models accounted for birth year, income, education, country of birth, smoking, diabetes mellitus, hypertension, and preeclampsia. The risk of maternal CVD increased with decreasing gestational age whereas the risk increase related to fetal growth appeared to be restricted to very small-for-gestational-age (SGA) infants. Compared with mothers of non-SGA infants born at term, the hazard ratio of CVD ranged from 1.39 (95% confidence interval 1.22-1.58) to 2.57 (95% confidence interval 1.97-3.34) among mothers to moderately and very preterm infants, respectively. There was a significant interaction between preterm birth and fetal growth with respect to mothers' risk of CVD (P<0.001). Among mothers to very SGA infants, the hazard ratio of CVD ranged from 1.38 (95% confidence interval 1.15-1.65) to 3.40 (95% confidence interval 2.26-5.11) in mothers to term and very preterm infants, respectively.

CONCLUSIONS: Delivery of a preterm or SGA infant is associated with later life maternal hospitalization or death from CVD even after accounting for socioeconomic factors, smoking, and pregnancy-related complications.