Risk factors of bronchopulmonary dysplasia depending on the severity of the disease in very preterm infants.

Bronchopulmonary dysplasia (BPD) remains a common pathology in very preterm infants. The risk of complications increases with the severity of the disease.The study aimed to determine the factors affecting the formation of moderate/severe BPD in the modern population of very preterm infants. Data from 201 very low birth weight infants < 32 weeks of gestation were used in a retrospective cohort study. Infants were retrospectively divided into two groups based on the type of respiratory support at 36 weeks of postmenstrual age (PMA) - 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/severe BPD was assessed. The groups were different in the incidence of intrauterine growth restriction (5% vs. 15%; p = 0.02), maternal hypertension (5% vs. 18%; p = 0.004), cesarean section (29% vs. 43%; p = 0.04), severe intraventricular hemorrhage (9% vs. 19%; p = 0.04), and retinopathy of prematurity (5% vs. 18%; p = 0.002), as well as in need for chest compressions during resuscitation at birth (2% vs. 9%; p = 0.01) for mild and moderate/severe BPD, respectively. Infants in the moderate/severe BPD group had lower Apgar scores at 1 and 5 min, required longer mechanical ventilation (220 (10-1904) hours vs. 72 (1-614) hours; p < 0.0001), CPAP duration (456 (16-1320) hours vs. 278 (10-1200) hours; p = 0.0002), oxygen supply (50 (3-146) days vs. 29 (2-68) days; p < 0.0001), as well as antibacterial therapy (61 (16-177) days vs. 52 (9-121) days; p = 0.0001) and hospital stay (109 (59-321) days vs. 85 (45-205) days; p < 0.0001). Infants with more severe BPD were also significantly more likely to die after reaching the PMA of 36 weeks (12% vs. 1%; p = 0.0003).According to the multivariable logistic regression analysis, the moderate/severe BPD was reliably and independently determined by maternal hypertension (aOR 4.53, 95% CI 1.48-13.91) and genitourinary infections (aOR 4.41, 95% CI 1.41-13.78), as well as the duration of CPAP (aOR 1.002, 95% CI 1.001-1.004) and mechanical ventilation (aOR 1.006, 95% CI 1.004-1.009). Duration of respiratory support is the main risk factor that determines the development of moderate/severe BPD in the modern population of very preterm infants. Maternal hypertension and genitourinary infections may influence the severity of lung injury.