Association of Chorioamnionitis and its Duration With Adverse Maternal Outcomes by Mode of Delivery: A Cohort Study

Objective To investigate the association of chorioamnionitis and its duration with adverse maternal outcomes by mode of delivery. Design A retrospective cohort study. Setting Data from the Consortium on Safe Labor Study in the USA (2002-2008). Population Singleton deliveries at ≥23 weeks of gestation (221 274 assessed deliveries, 62 331 by caesarean section). Methods The association of chorioamnionitis, and secondarily the duration of chorioamnionitis estimated from intrapartum antibiotic use, with adverse maternal outcomes was analysed using logistic regression with generalised estimating equations, adjusting for age, parity, race, pregestational diabetes, chronic hypertension, gestational age at delivery, study site and delivery year. Analyses were stratified by vaginal versus caesarean delivery. Main outcome measures The composite adverse maternal outcome included: postpartum transfusion, endometritis, wound/perineal infection/separation, venous thromboembolism, hysterectomy, admission to intensive care unit and/or death. Results Chorioamnionitis was associated with higher odds of the composite adverse maternal outcome with caesarean delivery (adjusted odds ratio 2.31; 95% CI 1.97-2.71); and the association persisted regardless of whether a woman had a trial of labour, preterm delivery or maternal group B streptococcus colonisation. The most common adverse outcomes after caesarean section were postpartum transfusion (56.0%) and wound/perineal infection or endometritis (38.6%). Chorioamnionitis was not associated with adverse maternal outcomes after vaginal delivery. The duration of chorioamnionitis as the exposure did not alter the association between chorioamnionitis and adverse maternal outcomes. Conclusions Chorioamnionitis, but not the estimated duration, was associated with increased odds of adverse maternal outcomes with caesarean delivery. This finding has implications for care programmes to prevent maternal morbidity after a caesarean section complicated by chorioamnionitis. Tweetable abstract Chorioamnionitis, but not its duration, increases the risk of adverse maternal outcomes with caesarean delivery.