Stratified Comparison of Risk Factors for Mild Versus Moderate-to-Severe Bronchopulmonary Dysplasia in Very Preterm Infants (< 32 Weeks Gestational Age)

BACKGROUND: Bronchopulmonary dysplasia (BPD) remains a significant complication in very preterm infants (< 32 weeks gestational age). Risk factors may differ between mild and moderate-to-severe BPD, but stratified analyses are limited. OBJECTIVE: To compare risk factors for mild versus moderate-to-severe BPD in very preterm infants (< 32 weeks gestational age). METHODS: This retrospective study analyzed data from very preterm infants (< 32 weeks gestational age) admitted to a tertiary neonatal intensive care unit between January 2017 and December 2024. BPD was classified as mild, moderate, or severe according to the 2001 NICHD/NHLBI criteria. Maternal, perinatal, and postnatal variables were compared between no-BPD, mild BPD, and moderate-to-severe BPD groups. RESULTS: Among 486 very preterm infants (< 32 weeks gestational age), 213 (43.8%) had no BPD, 147 (30.2%) had mild BPD, and 126 (25.9%) had moderate-to-severe BPD. After multivariate analysis, lower gestational age (aOR 1.92, 95% CI 1.63-2.26), male sex (aOR 1.68, 95% CI 1.14-2.48), and prolonged mechanical ventilation (aOR 1.21, 95% CI 1.14-1.29) were risk factors for both mild and moderate-to-severe BPD. However, histological chorioamnionitis (aOR 2.35, 95% CI 1.54-3.59), pulmonary hypertension (aOR 3.12, 95% CI 1.87-5.21), and postnatal sepsis (aOR 2.15, 95% CI 1.43-3.24) were significantly associated only with moderate-to-severe BPD. CONCLUSION: Risk factors for BPD in very preterm infants (< 32 weeks gestational age) differ by disease severity. Identifying severity-specific risk factors may help develop targeted prevention strategies and improve outcomes.