Objective: The purpose of this study was to quantify differences in indexes of pulmonary maturity between singleton and twin gestations by means of the TDx fetal lung maturity assay. Study Design: We identified records of a total of 830 singleton and twin

Objective: The purpose of this study was to describe morbidity, mortality, and developmental outcomes among extremely low-birth-weight infants (500-750 g). Study Design: This retrospective cohort study included 167 live-born infants born at Long Beach Memorial Medical Center between January 1990 and December 1995. Results: Mortality rates were 86% among infants <600 g and 44% among those ≥600 g, and the rate decreased with increasing gestational age. The absence of chorioamnionitis (P = .01) and the use of antepartum corticosteroids (P< .0001) or neonatal surfactant (P = .0001) were associated with survival. Sixty-four percent of studied infants had respiratory distress syndrome, and 17% had grade III or IV intraventricular hemorrhage. Among the 63 survivors 57% were tested at 30 months of corrected age with the Bayley Scales of Infant Development. Mild or significant delays were seen on the mental development index in 68% of these cases and on the psychomotor development index in 58% of cases. Conclusion: Morbidity and mortality rates and the rate of developmental delay among infants with birth weights between 500 and 750 g were significant. (Am J Obstet Gynecol 2000;182:1113-6.)