28-day survival rates of 6676 neonates with birth weights of 1250 grams or less.

Survival rates specific for birth weight, gestational age, sex, and race are described for 6676 inborn neonates who weighed less than 1251 g at birth and were born during 1986 through 1987. Overall 28-day survival increased with gestational age and birth weight, from 36.5% at 24 weeks' gestation to 89.9% at 29 weeks' gestation, or from 30.0% for neonates of 500 through 599 g birth weight to 91.3% for neonates of 1200 through 1250 g. The expected birth weight-specific survival advantage for female neonates and black neonates diminished when the data were controlled for gestational age, showing that certain previously reported survival advantages are based on lower birth weight for a given gestational age. Multivariate analysis showed that all tested variables were significant predictors for survival, in order of descending significance: gestational age and birth weight, sex, race, single birth, and small-for-gestational-age status. The powerful effect of gestational age on survival highlights the need for an accurate neonatal tool to assess the gestational age of very low birth weight neonates after birth.