Research based on hospital records demonstrates that many births class
ified as normal according to conventional demographic measurement are
intrauterine growth-retarded (IUGR) when evaluated clinically; also, i
n addition to birth weight and gestational age, it is necessary to foc
us on a third dimension, maturity, in analyses of birth outcomes. Alth
ough clinical studies allow more precise classification, the small num
ber of cases tends to result in unreliable estimates of rates and in l
oss of generalizability. The fetal growth ratio, a measure recently sh
own to be a valid proxy for maturity is used here to develop a classif
ication system based on combinations of weight, gestational age, and m
aturity, which we apply in a comparative analysis of a large data set.
The results show large differences ill the distribution of compromise
d births across racial and ethnic groups, as well as significant race/
ethnic differentials in the risk of infant mortality associated with a
dverse outcomes.