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

Abstract

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.

Keywords: cardiovascular morbidity; hospitalization; long term; pregnancy; preterm delivery.