Traditional risk factors underlie the racial disparity in infant mortality rates (365d, IMR) among term (37-42 wks) births: A population-based study

Background: The breadth of the racial disparity in IMR among term infants is incompletely understood. Objective: To determine whether known risk factors explain the racial disparity in IMR (including its neonatal and post-neonatal components) among term infants. Methods: Stratified and multivariable binomial regression analyses were performed on the 2003-2004 National Center for Health Statistics linked live birth-infant death cohort files. Only term African-American and non-Latino White infants with U.S.-born mothers were studied. Maternal variables examined included age, education, marital status, parity, prenatal care utilization, and region of birth. Results: The IMR of term African-American infants (N=782,452) exceeded that of term White infants (N=3,684,569): 4.1/1,000 vs. 2.4/1,000 respectively; RR=1.7 (1.7-1.8). In both races, congenital anomalies were the leading cause of infant death. African-American infants had a greater percentage of mothers with high-risk characteristics than White infants (p<0.01). However, the racial disparity in IMR abated among infants (N=271,350) born to married, college-graduated mothers who received adequate prenatal care. In multivariable binomial regression models, the adjusted RR of infant, neonatal (< 28d), and post-neonatal mortality (28-365d) for term African-American (compared to White) infants were 1.1 (1.1-1.2), 1.0 (1.0-1.1), and 1.1 (1.0-1.2), respectively. Conclusions: In the US, term African-American infants have a first year survival disadvantage compared to term non-Latino White infants. Most striking, well known maternal risk factors are the major determinant of this phenomenon. These findings highlight a component of the racial disparity in overall IMR directly amenable to basic public health intervention strategies.