Neonatal outcome comparisons between preterm infants with or without early pulmonary hypertension following prolonged preterm premature rupture of membranes before 25 gestational weeks in Korean Neonatal Network

Objective: To determine the outcomes of very low birth weight infants (VLBWIs) following maternal mid-trimester prolonged preterm premature rupture of membranes (PPROM) and subsequent early pulmonary hypertension (PH). Design: Prospective cohort study. Setting: A nationwide web-based registry of VLBWIs from 67 neonatal intensive care units. Patients: VLBWIs registered on the Korean Neonatal Network and born between 23 and 34 gestational weeks. Methods: VLBWIs exposed to maternal PPROM prior to 25 gestational weeks and lasting ≥7 days (PPROM25, n = 402) were matched 1:1 with infants not exposed or exposed within 24 h to PPROM (CON, n = 402), using propensity score matching. The PPROM25 group was subdivided into PPROM25 groups with or without early PH, defined as exposure to inhaled nitric oxide or other pulmonary vasodilators to treat PH within 3 days of life. Clinical variables and major outcomes were compared, and risk factors for mortality and morbidities were analyzed. Results: Of 1790 infants with maternal PPROM, the PPROM25 group comprised 402 (22.5%) infants. Survival rates were similar between the CON and PPROM25 groups (71.6% vs 74.4%); however, the incidence of bronchopulmonary dysplasia (BPD) differed (47.8% and 60.2%, p <.05). Infants in the PPROM25 group with early PH had higher mortality (55.6%) and more severe intraventricular hemorrhage (IVH) (31.7%) than infants in the PPROM25 group without early PH (21.9% and 14.3%, respectively; p <.05). In multivariate analysis, lower 5 min Apgar score and the presence of oligohydramnios increased the risk of development of early PH. The presence of PPROM25 was founded to be a significant risk factor for BPD and early PH in relation to mortality and severe IVH, respectively. Conclusions: In VLBWIs, prolonged exposure to maternal mid-trimester PPROM increased the risk of BPD. Subsequent early PH immediately after birth increased mortality and severe IVH, thus, requires special attention.