Risk Factors That Affect the Degree of Bronchopulmonary Dysplasia in Very Preterm Infants: A 5-year Retrospective Study

Background: Bronchopulmonary dysplasia(BPD) is one of the most common adverse consequence of premature delivery and the most common chronic lung disease in infants. BPD is related to long-term lung diseases and neurological development disorders, particularly respiratory and nervous system damage can be sustained to adulthood. The adverse effects caused by severe BPD are more prominent, but there were few studies on the risk factors of different degrees of BPD. Methods: This is a retrospective study of preterm infants born before 32 gestational weeks(GA) with bronchopulmonary dysplasia. Results: 250 preterm infants with BPD GA< 32 weeks were enrolle(137 boys[54.8 %] and 113 girls[45.2 %]). The birth weight ranged from 700g to 2010g (average birth weight 1318.52g). The GA was 25~31 +6 weeks (average GA 30.0 weeks). There were 39 (15.6 %), 185 (74.0 %) and 26 (10.4 %) cases of mild, severe and severe BPD respectively. There were significant differences in birth weight and in the rate of intrauterine asphyxia, pulmonary hemorrhage, neonatal respiratory distress syndrome (NRDS), circulatory failure, pulmonary hypertension, patent ductus arteriosus(PDA), pulmonary surfactant(PS), aminophylline, caffeine, glucocorticoids, tracheal intubation, diuretics, and parenteral nutrition length among the three groups( P <0.05). Birth weight(aOR=0.993,95% CI 0.989~0.997) and duration of parenteral nutrition(aOR=2.966,95% CI 1.992~4.415) are independent risk factors for the moderate BPD, and birth weight(aOR=0.997, 95% CI 0.995~0.999) , duration of parenteral nutrition(aOR=1.163, 95% CI 1.017~1.329), PDA (aOR=4.325, 95% CI 1.457~12.997) and aminophylline (aOR=4.882, 95% CI 1.661~14.350) are independent risk factors for the severe BPD, while caffeine (aOR=0.167, 95% CI 0.052~0.538)was a protective factor for severe BPD. Conclusion: Low birth weight and longer duration of parenteral nutrition were independent risk factors for moderate or severe BPD. PDA and aminophylline were independent risk factors of severe BPD, while caffeine was a protective factor for severe BPD. Trial registration retrospectively registered.