Perinatal risk factors for adverse long-term pulmonary outcome in premature infants: comparison of different definitions of bronchopulmonary dysplasia/chronic lung disease.

Background: The aim of the study was to determine factors that affect adverse long-term pulmonary outcome in premature infants.

Methods: This retrospective analysis was done using 306 clinical records of preterm singleton neonates at <32 weeks of gestation. Two definitions of adverse pulmonary outcome were used: chronic lung disease (CLD), defined as a need for supplemental oxygen for at least 28 days after birth; and bronchopulmonary dysplasia (BPD), defined as oxygen dependency for at least 28 days after birth plus at 36 weeks postmenstrual age and/or a need for positive-pressure ventilatory support. Selected perinatal variables were compared between these definitions, and factors related to disease development were identified on multivariate analysis.

Results: The incidence of CLD and of BPD were 42% and 17%, respectively. Regardless of the definitions, the incidence of patent ductus arteriosus and of neonatal infection were significantly higher in the patients who met the disease criteria, but that of chorioamnionitis and of small for gestational age (SGA) were significantly higher in the patients only when the BPD definition was applied. Multivariate analysis identified SGA as an independent risk factor for the development of BPD after controlling for gestational age.

Conclusions: Among selected perinatal variables, prenatal risk factors, particularly SGA, contributed to prolonged dependency on oxygen and/or positive-pressure ventilatory support, in combination with neonatal risk factors.