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

Over the past 20 years, very-low-birth-weight babies (born at or below 1,250 grams, about 2 lbs 12 oz) have had progressively better chances of survival. Factors such as sex and gestational age (weeks of pregnancy at birth) influence survival. Data on 6,676 newborns who weighed 1,250 grams or less were collected prospectively and analyzed. Survival rates were calculated specific for sex, race and birth weight; the usefulness of gestational age and birth weight for predicting survival at 28 days of age was also studied. Survival at 28 days increased with increasing gestational age and birth weight. At 24 weeks gestational age, survival was 36.5 percent and at 29 weeks it rose to 89.9 percent. Babies with birth weights between 500 and 599 grams (17.5 to 21 oz) had a 30 percent chance of survival at 28 days; this rose to 19.3 percent survival at birth weights of 1,200 to 1,250 grams. When the effect of gestational age was controlled for statistically, it was found that a previously reported survival advantage for females and black infants was not as great as expected. All tested variables were significant predictors for survival. Listed in order of descending significance, they were: gestational age and birth weight, sex, race, single birth, and small-for-gestational-age status. The important effect that gestational age exerts on survival reaffirms the need to have an accurate method of assessing gestational age by physical examination at the time of birth for very-low-birth-weight infants. (Consumer Summary produced by Reliance Medical Information, Inc.)