Preterm prelabour rupture of membranes: effect of latency on neonatal and maternal outcomes

To compare risks of infection and prematurity-related outcomes according to latency periods among women with preterm prelabour rupture of membranes (PPROM).

Women with PPROM occurring between 24+0 and 36+6 weeks of gestation were identified from a provincial population-based perinatal database in Nova Scotia. The primary outcomes included composite variables for serious maternal and neonatal infectious morbidity and neonatal prematurity-related morbidity. Logistic regression was used to quantify the relationship between latency period (< 24 hours, 24 hours to < 48 hours, 48 hours to < 7 days, and ≥ 7 days) and maternal and neonatal outcomes. Separate analyses were conducted for gestational age groups 24+0 to 33+6 weeks and 34+0 to 36+6 weeks.

There were 4329 women included in the cohort. The composite variables representing serious maternal or neonatal infectious morbidity were not significantly associated with latency for either gestational age group. For PPROM occurring at gestational ages of 24+0 to 33+6 weeks, the odds of neonatal prematurity-related morbidity were significantly decreased at the latency periods of 48 hours or more compared with < 24 hours latency. For PPROM at 34+0 to 36+6 weeks of gestation, the odds of prematurity-related morbidity at 48 hours to < 7 days latency was decreased compared with latencies < 24 hours (OR 0.4; 95% CI 0.2 to 0.8).

Postponing delivery following PPROM may contribute to less prematurity-related morbidity, even close to term, without putting mother or neonate at substantial risk for serious infectious morbidity. Generalization of these findings to other obstetric populations should be informed by the underlying risk of infection.