INTRODUCTION: A recent scoping review identified histological chorioamnionitis (HCA), small for gestational age (SGA), and bubbly/cystic appearance on chest X-ray (bubbly/cystic CXR) as risk factors for severe bronchopulmonary dysplasia (BPD). To further validate these results, a large-scale database was analyzed. METHODS: This retrospective multicenter cohort study included infants born at <
28 weeks' gestational age between 2003 and 2016. The validated risk factors identified from the scoping review were analyzed for independent associations with severe BPD using multivariable logistic regression. Additionally, the association of these factors with long-term outcomes at 3 years, including home oxygen therapy (HOT) and neurodevelopmental impairments (NDIs), were analyzed. RESULTS: Among 15,834 extremely preterm infants, HCA, SGA, and bubbly/cystic CXR on postnatal day 28 were significantly and independently associated with severe BPD (adjusted odds ratio, 1.20
95% confidence interval, 1.06-1.36) (1.73
1.51-1.98) (1.79
1.60-2.01), respectively. These three factors were also linked to HOT at 3 years (1.54
1.14-2.08) (1.70
1.21-2.39) (2.63
1.94-3.56), respectively. Their combination significantly increased the prevalence of severe BPD and HOT at 3 years, particularly with bubbly/cystic CXR. Only SGA was independently associated with NDIs in BPD infants (1.55
1.32-1.83). CONCLUSIONS: HCA, SGA, and bubbly/cystic CXR on postnatal day 28 were identified as important risk factors for severe BPD and long-term respiratory outcomes. While further research is needed to validate their role in endotype-specific classification of BPD, these findings may contribute to early prognostic strategies and targeted interventions before 36 weeks' postmenstrual age.