The study aimed to determine the factors affecting the formation of moderate to severe BPD in the modern population of very preterm infants. Infants were retrospectively divided into two groups based on the type of respiratory support at 36 weeks of postmenstrual age – mild BPD (133 infants) and moderate/severe BPD (68 infants). The influence of major perinatal risk factors, neonatal morbidity, and medical interventions on the development of moderate to severe BPD was assessed. The study identified factors that contribute to more severe lung injury in preterm infants born at <32 weeks gestation.