Understanding racial and ethnic disparities in U.S. infant mortality rates.

In the United States, different racial and ethnic groups have very different infant mortality patterns. When assessing the relative contribution of the percentage of preterm births and gestational age-specific infant mortality rates to racial and ethnic infant mortality differences, we found that for non-Hispanic black women, 78 percent of their elevated infant mortality rate compared with non-Hispanic white women was due to their higher percentage of preterm births, while 22 percent was due to higher gestational age-specific infant mortality rates (primarily at 34 weeks of gestation or more). For Puerto Rican women, their elevated infant mortality rate compared with non-Hispanic white women was entirely due to their higher percentage of preterm births. However, AIAN women had a very different infant mortality pattern: 76 percent of their higher infant mortality rate compared with non-Hispanic white women was due to their higher gestational age-specific infant mortality rates (primarily at 34 weeks or more), and only 24 percent was due to their higher percentage of preterm births.These findings are consistent with the cause-of-death analysis, which found that for bothnon-Hispanic black and Puerto Rican women, most of their higher infant mortality rate compared with non-Hispanic white women was due to preterm-related causes. In contrast, for AIAN women, the infant mortality rate from SIDS was 2.4 times, and the rate from unintentional injuries was 2.3 times, the non-Hispanic white rate. Infant mortality rates for non-Hispanic black women would be reduced by 71 percent, those for AIAN women by 64 percent, and those for Puerto Rican women by 67 percent if rates from preterm-related causes, congenital malformations, SIDS, and unintentional injuries could be reduced to non-Hispanic white levels.The different infant mortality patterns for non-Hispanic black, Puerto Rican, and AIAN women suggest different prevention strategies (6,7). In addition, because the percentage of preterm births for all U.S. racial and ethnic groups is higher than in other developed countries, all U.S. racial and ethnic groups might benefit from prematurity prevention efforts (8,9).