Respiratory trajectory and risk of death or moderate-to-severe bronchopulmonary dysplasia in very preterm infants: a nine-year cohort study.

Aim: To evaluate factors associated with death before 36 weeks' postmenstrual age (PMA) or moderate-to-severe bronchopulmonary dysplasia (BPD) in very preterm infants while accounting for survivor bias. Methods: This retrospective cohort study included infants born at <32 weeks' gestation and admitted to a tertiary neonatal intensive care unit between January 2017 and December 2025. The primary outcome was death before 36 weeks' PMA or moderate-to-severe BPD. Baseline characteristics, neonatal morbidities, and respiratory support variables were examined. Multivariable logistic regression was performed using a sequential modelling approach incorporating early clinical variables and subsequent respiratory-course variables. Results: Among 1,259 infants, 1,253 had complete outcome data and were included in the analysis; the composite outcome occurred in 27.1%. Risk decreased progressively with advancing gestational age, from 80.2% in infants born at <26 weeks to 11.7% at 30-31 weeks ( Conclusions: In very preterm infants, lower gestational age and prolonged invasive ventilation were the principal factors associated with death or moderate-to-severe BPD. Associations involving respiratory escalation therapies likely reflected greater underlying illness severity and evolving respiratory trajectory.