Proportional Differences in Births and Infant Mortality Rates among the Triethnic Population in Texas from 1984 through 1986

Birth at preterm gestation and/or with low birth weight is a major predictor of the infant mortality rate, which is twice as high in African-American as in Anglo and Hispanic infants in Texas. This study examined the relative proportions of Anglo, African-American, and Hispanic births that occurred in Texas at specific gestational ages and birth weights, and the neonatal, postneonatal, and infant mortality rates associated with those births. African-American infants showed a systematic tendency to be born at earlier gestational ages and with lower birth weights than did Anglo infants, while Hispanic-Anglo differences were limited to a small excess of preterm but not low weight Hispanic births. Preterm and low-birth-weight African-American infants had neonatal and infant mortality rates that were lower than those of Anglo infants, but that benefit was inadequate to compensate for the greater proportion of African-American births that were at risk. No consistent difference could be identified between Hispanic and Anglo infant mortality rates. We conclude that the birth weight and gestational age predictors of infant mortality reflect the combined effects of two ethnic-specific factors: the mortality rates at specific birth weights and gestational ages, and the proportions of births that are at risk. The biological and/or sociological causes for these ethnic differences in pregnancy outcomes and mortality risk need to be identified if the mortality rate of African-American infants in Texas is to be reduced