Mortality and morbidity in infants with intrauterine growth retardation.

This report is based on an analysis of the experience with all births in several urban and rural areas of the United States. All infants whose birth weight was in the lowest quartile for their week of gestation were designated as small for gestational age regardless of their birth weight or length of gestation; other infants were considered appropriate for gestation age. We interpret the data to indicate that appropriate-for-gestational age and small-for-gestational age infants, all of low birth weight, differ in the nature of their risk for adverse outcome as determined by an assessment at one year of age, although both are at approximately equal risk of adverse outcome overall. In each weight group, the total proportion of infants who either died before one year of age or were handicapped at one year of age was similar for small-for-gestational age and appropriate-for-gestational age infants, but appropriate-for-gestational age infants were at greater risk of neonatal death and small-for-gestational age infants were at greater risk of problems manifested during the first year of life or at one year of age. As the findings are based on data obtained from entire populations (rather than from infants born in particular hospitals), they are likely to be generalizable.