Considerations in evaluating changes in outcome for infants weighing less than 1,501 grams.

Neonatal mortality for 285 infants and developmental outcome for 158 infants with birth weights of 751 to 1,500 gm, born in the Capital Regional Perinatal Center between July 1975 and December 1979, were compared with the findings in 1952, in 1965 to 1967, and in 1968 to 1970. In the 1,001- to 1,500-gm group, mortality decreased and there was an 18% incidence of major neuropsychiatric disability compared to the 48% found in 1952 when the same examination techniques and diagnostic criteria were used. More 751- to 1,000-gm infants survive now also, but 40% have a major handicap. There is a high incidence of preconceptional, prenatal, perinatal, and postnatal abnormalities in this group of very low-birth-weight infants, but the incidence is significantly higher in those with major disabilities. The infants who die and those who have subsequent major neuropsychiatric abnormalities require the sophisticated techniques of neonatal intensive care, whereas these procedures are not needed or are used only briefly for the infants who are normal. In upper New York State, the demographic shifts in race, age, parity, education, and induced abortions account for 13% of the drop in neonatal mortality in the 1,001- to 1,500-gm group. These demographic as well as social and medical care changes must be taken into account in any evaluation of the decreasing mortality and morbidity that has occurred. Improvements in prenatal, obstetric, and neonatal care appear to be doing for the 751- to 1,000-gm group now what the then high-level care in 1952 did for the 1,001- to 1,500-gm group, when mortality decreased but only half of those who survived were normal.