Bronchopulmonary dysplasia in very and extremely low birth weight infants - analysis of selected risk factors.

AIM: The aim of the study was to analyze the role of specific risk factors affecting the development and clinical course of BPD in infants born before 32 weeks of gestation with a birth weight ≤ 1500g. MATERIALS AND METHODS: The study included 222 infants born and hospitalized at the Department of Neonatology, Polish Mother's Memorial Hospital-Research Institute. At their 28-th day of life, the patients were divided into two groups: with and without BPD. The grade of BPD severity was determined at 36 weeks of postmenstrual age. RESULTS: BPD was diagnosed in 117 (52.7%) of infants, 65 (55,6%) of them developed its mild, 29 (24,8%) moderate and 23 (19,7%) severe form. Infants with BPD had significantly lower gestational age than those without BPD: 27.0 weeks (IQR 26.0-28.3 weeks) vs. 30.0 weeks (IQR 29.3-31.0 weeks), and lower birth weight: 900g (IQR 740.0-1050.0g) vs. 1290g (IQR 1100.0-1370.0g). A significantly lower gestational age R=-0.70, p < 0.0001 and birth weight R=-0.66, p<0.0001 were observed in correspondence with the increase of BPD severity. In BPD group there were 72 (61.5%) male infants, whereas in that without BPD 54 (51.4%) of them, p=0.1290. In the group with mild form of BPD, there were 29 (44.6%) males, with moderate 23 (79.3%) and severe 20 (87.0%), p=0.0002. A statistically significant difference was found for: respiratory distress syndrome 116 (99.2%) vs. 83 (79.1%), p<0.0001, congenital infection 70 (59.8%) vs. 40 (38.1%), p=0.0012, patent ductus arteriosus 61 (52.1) vs. 28 (26.7), p=0.0001, complete prenatal steroid therapy 77 (65.8%) vs. 85 (81.0%), p=0.0112 and Apgar score of 1 min., p<0.0001 and 5 min., p<0.0001. In the group with BPD significantly more frequent were: intraventricular hemorrhage 87 (74.4%) vs. 37 (35.2%), p<0.0001, periventricular leukomalacia 11 (9.4%) vs. 0 (0.0%) p=0.0009 and retinopathy of prematurity 47 (40.2%) vs. 6 (5.7%), p<0.0001. No statistical significance was found for: premature rupture of membranes, the route of delivery, Ureaplasma spp. infection and necrotizing enterocolitis. Independent factors affecting the risk of BPD are: gestational age (OR 0.3213, p<0.0001), birth weight (OR 0.9968, p=0.0036), and respiratory distress syndrome (OR 3.9388; p=0.0142). CONCLUSIONS: Lower gestational age, low birth weight, respiratory distress syndrome, Apgar score, congenital infection, lack of prenatal steroid therapy, patent ductus arteriosus and male gender are the risk factors for the development of BPD.