Data from a 1985 stratified sample of urban hospitals with neonatal intensive care units show that over half of the low-birth-weight infants in the United States are cared for in such centers. A cost analysis focusing on all infants who survive and go home from these hospitals revealed that those weighing from 500-2,500 g represent nine percent of the neonatal patient load, but consume 57 percent of the cost of their hospital care. Similarly, neonates in the 500-1,499 g range account for 1.6 percent of the infants cared for and over one-third or related costs in these urban facilities. If only 20 percent of infants moved from one birth-weight group (in 250 g intervals) to the next, this upward shift would result in an immediate savings of $70-$95 million. Estimates based on the published literature indicate that the programmatic expenditures for prenatal care needed to cause this shift would be $9-$28 million less than these immediate savings.