Compromised birth outcomes and infant mortality among racial and ethnic groups.

Research based on hospital records demonstrates that many births classified as normal according to conventional demographic measurement are intrauterine growth-retarded (IUGR) when evaluated clinically; also, in addition to birth weight and gestational age, it is necessary to focus on a third dimension, maturity, in analyses of birth outcomes. Although clinical studies allow more precise classification, the small number of cases tends to result in unreliable estimates of rates and in loss of generalizability. The fetal growth ratio, a measure recently shown to be a valid proxy for maturity, is used here to develop a classification system based on combinations of weight, gestational age, and maturity, which we apply in a comparative analysis of a large data set. The results show large differences in the distribution of compromised births across racial and ethnic groups, as well as significant race/ethnic differentials in the risk of infant mortality associated with adverse outcomes.