Effect of birth weight, race, and sex on survival of low-birth-weight infants in neonatal intensive care

Survival for low-birth-weight infants has traditionally been analyzed by birth weight categories spanning considerable ranges of weight. We developed a finer description of survival rates to allow estimation of survival percentages for infants of any specific birth weight between 500 and 2500 gm. Our sample consisted of 16,183 infants treated in tertiary neonatal intensive care between 1980 and 1987. Their survival data were analyzed by 50 gm increments between 500 and 2500 gm, and a continuous survival curve was constructed by log linear regression methods. Mortality differences between males and females and blacks and whites were analyzed. Survival for females was higher than males between 500 and 1500 gm and higher for blacks than whites between 650 and 1500 gm. Between 1500 and 2500 gm, no significant effects of birth weight, race, or sex were observed, with survival remaining stable at approximately 95% across all combinations of variables.