Objective: Our purpose was to determine the incidence of significant neonatal morbidity in fetuses with documented pulmonary maturity delivered before 37 weeks' gestation.
Study design: A retrospective review of 213 pregnancies with documented fetal lung maturity (lecithin/sphingomyelin ratio > or = 2.0 or phosphatidylglycerol present) and delivery before 37 weeks was performed. The incidence of neonatal respiratory distress syndrome, bronchopulmonary dysplasia, grade 3 or 4 intraventricular hemorrhage, necrotizing enterocolitis, patent ductus arteriosus, retinopathy of prematurity, infectious morbidity, hyperbilirubinemia, and admission to the special care nursery was determined for those pregnancies with intact membranes and preterm premature rupture of membranes.
Results: Serious neonatal morbidity declined with advancing gestational age and was less common after 32 completed weeks of pregnancy. Although the frequencies of respiratory distress syndrome, grade 3 or 4 intraventricular hemorrhage, and necrotizing enterocolitis were 19.4% (12/62), 8.1% (5/62), and 4.8% (3/62), respectively, at < or = 33 weeks' gestation, one case of respiratory distress syndrome, one case of grade 3 intraventricular hemorrhage, and one case of necrotizing enterocolitis occurred in the 151 neonates born at > or = 34 weeks' gestation.
Conclusions: In spite of fetal lung maturity major neonatal morbidity was observed in our patient population. These data relating neonatal morbidity to gestational age are useful in the critical decision regarding timing of delivery.