An association between preterm delivery and long-term maternal cardiovascular morbidity

Objective The purpose of this study was to investigate whether a history of preterm delivery (PTD) poses a risk for subsequent maternal long-term cardiovascular morbidity. Study Design A population-based study compared the incidence of cardiovascular morbidity in a cohort of women who delivered preterm (<37 weeks' gestation) and those who gave birth at term at the same period. Deliveries occurred during the years 1988-1999 with follow up until 2010. Kaplan-Meier survival curves were used to estimate cumulative incidence of cardiovascular hospitalizations. Cox proportional hazards models were used to estimate the adjusted hazard ratios for cardiovascular hospitalizations. Results During the study period 47,908 women met the inclusion criteria; 12.5% of the patients (n = 5992) delivered preterm. During a follow-up period of >10 years, patients with PTD had higher rates of simple and complex cardiovascular events and higher rates of total cardiovascular-related hospitalizations. A linear association was found between the number of previous PTD and future risk for cardiovascular hospitalizations (5.5% for ≥2 PTDs; 5.0% for 1 PTD vs 3.5% in the comparison group; P <.001). The association remained significant for spontaneous vs induced PTD and for early (<34 weeks) and late (34 weeks to 36 weeks 6 days' gestation) PTD. In a Cox proportional hazards model that adjusted for pregnancy confounders such as labor induction, diabetes mellitus, preeclampsia, and obesity, PTD was associated independently with cardiovascular hospitalizations (adjusted hazard ratio, 1.4; 95% confidence interval, 1.2-1.6). Conclusion PTD is an independent risk factor for long-term cardiovascular morbidity in a follow-up period of more than a decade.