Objective: The purpose of this study was to evaluate whether infants who were delivered at <28 weeks of gestation after prolonged latency in pregnancies that were complicated by preterm premature rupture of membranes are at increased risk of histologic chorioamnionitis and intracranial ultrasound abnormalities.
Study design: A retrospective cohort analysis of 430 singleton infants born at <28 weeks of gestation in five hospitals (January 1991 through December 1993) with at least one of three protocol cranial scans read by a consensus committee and with placental pathologic evidence. Outcome variables were placental (histologic chorioamnionitis, fetal vasculitis) and neonatal (intraventricular hemorrhage, echolucencies, ventriculomegaly). Latency was divided into five intervals, and outcomes in the longer four intervals were compared with those in infants who were delivered at <1 hour after membrane rupture. Each outcome-latency relationship was evaluated in a logistic model that was controlled for confounders.
Results: Odds ratios and CIs for each latency interval that was controlled for confounders that included gestational age, maternal race, antenatal steroid and antibiotic administration, and delivery mode show a statistically significant increase in the risk of histologic chorioamnionitis and fetal vasculitis. Models for intraventricular hemorrhage, ventriculomegaly, and echolucencies failed to demonstrate significant differences with increasing latency.
Conclusions: Ascending transcervical infection after preterm premature rupture of membranes is documented by the increasing odds ratios of placental inflammation. The odds of ultrasonically detectable brain abnormalities, however, did not increase with increasing latency.