Perinatal factors and the development of chronic lung disease in preterm infants: a case control study.

A case control study of neonates was performed to determine those factors contributing to the development of chronic lung disease (CLD). During the 5 years 1981-84 there were 487 neonatal survivors at gestations of 25-32 weeks; 391 of these developed respiratory failure (oxygen therapy required for more than 6 h). Fifty-six of the latter developed CLD (oxygen therapy required for more than 28 days and a coarse reticular pattern on chest X-ray). These neonates were predominantly of the shortest gestational ages, regardless of the initial chest X-ray diagnosis. Forty-three of these infants with CLD were matched for gestation and initial chest X-ray appearance (respiratory distress syndrome, n = 20; normal, n = 15; non-specific, n = 8) with 42 control infants. The mean duration of oxygen therapy (P less than 0.001), maximum FiO2 (P less than 0.001), incidence (P less than 0.01) and duration of intermittent positive pressure respiration (IPPR; P less than 0.05) and peak IPPR (P less than 0.05) were significantly greater in the CLD group. Mean birthweight (P less than 0.001), arterial cord pH (P less than 0.05) and base excess (P less than 0.05) were significantly lower in the CLD group. Factors that were not statistically significant in the development of CLD included antenatal fetal heart rate abnormality, hypertensive disease of pregnancy, acute intrauterine infection (chorioamnionitis or umbilical vasculitis), administration of antenatal steroids, sex, patent ductus arteriosus and pneumothorax. The association between CLD and ventilator/oxygen therapy is confirmed. Contrary to other reports, male sex, clinical patent ductus arteriosus and pneumothorax were not associated with CLD.