Mortality and morbidity of 500- to 1,499-gram birth weight infants live-born to residents of a defined geographic region before and after neonatal intensive care.

All very low-birth-weight infants live-born to residents of an urban southern Ontario county were studied before (1964 to 1969) and after (1973 to 1977) the introduction of neonatal intensive care. Mortality at hospital discharge decreased from 89.4% to 77.6% among infants whose birth weights were 500 to 999 gm and from 37.6% to 22.8% among infants with birth weights of 1,000 to 1,499 gm. The families of 121/150 (81%) and 134/151 (89%) of all children from the two cohorts who were discharged from the hospital alive were surveyed. At follow-up 7/121 (6%) and 4/134 (4%) had died. Major damage was reported for 13/121 (11%) and 18/134 (13%) of the children. Neonatal intensive care was associated with a significant reduction in mortality but there has not been a significant change in morbidity.