352 - Effects of rescue betamethasone on bronchopulmonary dysplasia in infants born < 32 weeks in the setting of preterm premature rupture of membranes.

Publication Number: 2341.352

Madalyn Lutz, UPMC Childrens Hospital of Pittsburgh, Imperial, PA, United States; Christina Megli, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Danielle Browning, UPMC Childrens Hospital of Pittsburgh, Pittsburgh, PA, United States; Alexander Boscia, MD, UPMC Magee-Womens Hospital, Pittsburgh, PA, United States

Background: Bronchopulmonary dysplasia (BPD) remains a major cause of morbidity and mortality among infants born < 32 weeks' gestation. Its pathogenesis reflects disrupted alveolarization and abnormal vascular growth, driven by antenatal inflammation, infection, and postnatal ventilator and oxygen exposure. Infants born to mothers with preterm premature rupture of membranes (PPROM) are uniquely vulnerable due to prolonged intrauterine inflammation, oligohydramnios, and extended latency. This chronic inflammatory phenotype differs from acute chorioamnionitis and remains understudied.

Objective: To evaluate whether a single rescue course of betamethasone (BMZ) is associated with improved survival and reduced incidence or severity of BPD among PPROM pregnancies delivering between 23 0/7-31 6/7 weeks' gestation.

Design/Methods: We conducted a retrospective cohort study of mother-infant dyads with PPROM identified by ICD-9 codes from July 2015-July 2020. Exclusions included congenital anomalies, presentation in active preterm labor, delivery within 12 hours of membrane rupture, and gestational age < 23 or ≥32 weeks. The final analytic cohort comprised 241 infants. Manual chart review captured >30 maternal and neonatal variables, including gestational age, birth weight, latency duration, infection markers, BMZ exposure, and respiratory support. The primary exposure was rescue BMZ, defined as a repeat corticosteroid course after an initial full course. The primary outcome was survival to discharge without moderate to severe BPD, as defined by Jensen criteria.

Results: Nearly all infants (n=238) received an initial BMZ course; among those eligible, 49 received rescue BMZ. Baseline characteristics were similar between exposure groups. A diagnosis of any BPD occurred in 28% of infants without rescue BMZ versus 25% of those with rescue BMZ. Among 36 infants with moderate-to-severe BPD, 27% had received rescue BMZ and 73% had not. These differences were not statistically significant.

Conclusion(s): In this single-center PPROM cohort, a single rescue BMZ course was not associated with statistically significant reductions in BPD incidence or severity. However, the trend toward lower BPD rates in the rescue group suggests potential benefit that may not have reached significance due to limited sample size. These findings highlight the need for larger, multicenter studies to clarify the role of rescue corticosteroids to help optimize antenatal steroid guidelines and improve pulmonary outcomes for very preterm infants.

Table 1. Baseline Demographics and Characteristics of Neonates
Two-sample t-test, Wilcoxon ran-sum test, Pearson Chi-square test; Mean SD; median [IQR]. The mean gestational age at birth for both groups was 29 weeks and the mean birth weight was 1200g. Overall, there were no statistically significant differences amongst the two groups of neonates. Infants that did not receive rescue betamethasone (rBMZ) had higher rates of BPD overall that those that did receive rBMZ however, this was not statistically significant. Interestingly, when looking at the group that received rBMZ, a higher percentage were diagnosed with moderate to severe BPD when comparing to the entire cohort. However, when only looking at the infants diagnosed with moderate to severe BPD, those that did not receive rBMZ made up a higher percentage than those that did receive rBMZ (27% vs. 72%). This was not statistically significant.