摘要：Objectives. We evaluated whether the decline of the racial disparity in preterm birth during the last decade was commensurate with a decline in the contribution of preterm birth to the infant mortality gap. Methods. We used linked files of 1990 and 2000 data on US infant births and deaths to partition the gap between Black and White infant mortality rates into differences in the (1) distribution of gestational age and (2) gestational age–specific mortality rates. Results. Between 1990 and 2000, the Black–White infant mortality rate ratio did not change significantly (2.3 vs 2.4). Excess deaths among preterm Black infants accounted for nearly 80% of the Black–White infant mortality gap in both 1990 and 2000. The narrowing racial disparity in the preterm birth rate was counterbalanced by greater mortality reductions in White than in Black preterm infants. Extremely preterm birth (<28 weeks) was 4 times higher in Black infants and accounted for more than half of the infant mortality gap. Conclusions. Substantial reductions in the Black–White infant mortality gap will require improved prevention of extremely preterm birth among Black infants. In the United States, nearly two thirds of low-birthweight infants and nearly all very-low-birthweight infants are born preterm. 1 Preterm birth is a leading cause of infant morbidity and mortality and is associated with numerous familial, social, and economic costs related to intensive medical care and the developmental deficits of surviving very preterm infants. The immediate economic costs of preterm birth alone have been estimated to exceed $15 billion annually; this represents half of all infant hospital charges. 2 The burden of adverse perinatal events and sequelae, including preterm birth and infant death, is not equally distributed by race. 3 , 4 Black infants are consistently more than twice as likely as White infants to die within the first year of life. Previous analyses of 1983, 1988, and 1991 infant mortality data suggest that almost two thirds of the racial disparity in infant mortality can be attributed to preterm birth, using very-low-birthweight as a proxy. 5 – 7 However, the specific contribution of excess preterm births among Black infants to this gap has not been directly examined. During the last decade, the racial disparity in preterm birth has declined because of an increase in the preterm birth rate among White infants and a decrease in the preterm birth rate among Black infants. 8 – 10 However, the more than double Black–White infant mortality rate ratio has remained unchanged; mortality rates have declined approximately 20% among both Black and White infants. 3 We examined whether and how the contribution of preterm birth to the Black–White disparity in infant mortality may have changed between 1990 and 2000. We used methods similar to previous birthweight-specific analyses to examine how changes in both the distribution of gestational age and gestational age–specific mortality rates have contributed to the infant mortality disparity over time. We focused on gestational age and the degree of preterm birth because it is a more specific outcome than birthweight, which is a product of both gestational age at delivery and the fetal growth rate.
