Severe adverse maternal outcomes associated with chorioamnionitis

BACKGROUND: Chorioamnionitis complicates 1-5% of all pregnancies and is associated with substantial neonatal morbidity. Prolonged labor and increased use of labor induction may lead to increased rates of chorioamnionitis. OBJECTIVE: We sought to quantify serious adverse maternal outcomes that are associated with chorioamnionitis in a contemporary population of live births in the state of Ohio. STUDY DESIGN: We conducted a population-based retrospective cohort study of all live births in Ohio (2006-2015). Maternal demographic and obstetric outcomes, as reported on the US birth certificate, were compared between women with and without chorioamnionitis. Primary study outcomes were maternal intensive care unit admission and composite adverse maternal outcome (intensive care unit admission, blood product transfusion, unplanned hysterectomy, unplanned operation after delivery, or ruptured uterus). Multivariate logistic regression estimated the relative association of chorioamnionitis with maternal adverse outcomes. RESULTS: Of 1,393,054 live births in Ohio over 10 years, 17,430 live births (1.3%) had chorioamnionitis. Women with chorioamnionitis had significantly higher rates of maternal intensive care unit admission (0.5% vs 0.1%; P<.001) and composite adverse outcome (5.0% vs 1.5%; P<.001) compared with those without chorioamnionitis. Even after adjustment for coexisting risks, chorioamnionitis was associated with 2- to 3-fold increased risk of composite adverse outcome, maternal intensive care unit admission, blood transfusion, ruptured uterus, and unplanned operation after delivery. Sensitivity analysis that excluded women who delivered by cesarean section revealed persistent significant associations between chorioamnionitis and adverse maternal outcomes. The rate of composite adverse outcomes was higher at earlier gestational ages. However, the relative risk increase of adverse outcome was more pronounced with advancing gestational age at delivery. CONCLUSION: The frequency of severe adverse outcomes in pregnancies that are complicated with chorioamnionitis is high, with 1 in every 20 cases affected, and includes an almost 3-fold increased risk for maternal intensive care unit admission compared with patients without chorioamnionitis. Efforts to prevent and treat chorioamnionitis to minimize maternal risk could be an important area of focus in the reduction of the rate of severe maternal morbidity in the United States.