(412) Previable Premature Rupture of the Membranes and Neonatal Mortality/Morbidity in a National Retrospective Cohort

Objective: Counselling after previable preterm premature rupture of the membranes (PPROM) is challenging due to older previable PPROM cutoffs and small studies. Our objective was to assess neonatal mortality/morbidity after previable PPROM < 22 weeks versus no PPROM to assist in counselling at viability and decision making.

Study Design: We conducted a retrospective cohort study of liveborn singletons born < 32 wk’ gestation from 2018-2022, who received active resuscitation (including delivery room deaths), or did not need it, and were admitted to a neonatal intensive care unit within the Canadian Neonatal/Preterm Birth Network database. Among previable PPROM infants, gestational age at birth and latency period were determined. Our primary outcome was a composite of neonatal mortality or severe morbidity consisting of any one or more of severe respiratory distress syndrome, severe intraventricular hemorrhage, severe necrotizing enterocolitis, severe retinopathy of prematurity, moderate/severe bronchopulmonary dysplasia, cystic periventricular leukomalacia or sepsis. Outcomes were compared between infants with and without previable PPROM < 22 wk, using generalized estimating equations to account for hospital effect and adjusting for confounders and covariates.

Results: As onset of previable PPROM (n=225) increased from ≤16 to 21 wk’ gestation, median gestational age at birth decreased from 27.5 wk (IQR 24.5, 29.0) to 25.0 (IQR 23.0, 28.0) and latency period decreased from 86.5 days (IQR 63.5, 98.0) to 30.0 (IQR 15.0, 49.0, Table 1). Infants with previable PPROM had increased odds of neonatal mortality/severe morbidity (90%), compared to those without (66%, n=7846, adj OR 1.71, 95% CI 1.14 to 2.56, Table 2). There was a trend toward more sepsis with previable PPROM at 21 wk than earlier.

Conclusion: In a large, contemporary cohort of previable PPROM (< 22 wk) reaching viability, an inverse relationship was seen between timing of rupture and gestational age at birth, decreasing from a median of 27.5 to 25 wk. Almost all previable PPROM infants experienced mortality/morbidity, almost double the odds without PPROM.