Trends in Racial and Ethnic Disparities in Infant Mortality Rates in the United States, 1989-2006

Objectives. We sought to measure overall disparities in pregnancy outcome, incorporating data from the many race and ethnic groups that compose the US population, to improve understanding of how disparities may have changed over time. Methods. We used Birth Cohort Linked Birth-Infant Death Data Files from US Vital Statistics from 1989-1990 and 2005-2006 to examine multigroup indices of racial and ethnic disparities in the overall infant mortality rate (IMR), preterm birth rate, and gestational age-specific IMRs. We calculated selected absolute and relative multigroup disparity metrics weighting subgroups equally and by population size. Results. Overall IMR decreased on the absolute scale, but increased on the population-weighted relative scale. Disparities in the preterm birth rate decreased on both the absolute and relative scales, and across equally weighted and population-weighted indices. Disparities in preterm IMR increased on both the absolute and relative scales. Conclusions. Infant mortality is a common bellwether of general and maternal and child health. Despite significant decreases in disparities in the preterm birth rate, relative disparities in overall and preterm IMRs increased significantly over the past 20 years.