Postterm delivery among African Americans, Mexican Americans and Whites in Chicago

The purpose of the present study was to examine the effect of individual-level and community-level risk factors on the postterm delivery rates of infants born to African-American, Mexican-American, and non-Latino White mothers; and to compare postterm delivery rates between these ethnic groups.

This is a population-based study.

We performed stratified and multivariate logistic regression analyses on a linked dataset of 1992-1995 Illinois vital records, 1990 United States Census income data, and 1995 Chicago Department of Public Health information. Communities with one or more high-risk characteristics (low median family income or high rates of unemployment, homicide or lead poisoning) were classified as impoverished.

In Chicago, African Americans (N = 85,978) had a postterm rate of 4.3/1,000 and Mexican Americans (N = 47,266) had a postterm rate of 3.6/1,000, compared to 2.3/1,000 for non-Latino Whites (N = 48,601); relative risk (ninety-five percent confidence interval) = 1.9 (1.5-2.3) and 1.6 (1.2-2.0), respectively. Maternal age, education, marital status, parity, and prenatal care usage were associated with ethnic group-specific postterm delivery rates. In a multivariate logistic regression model for non-impoverished mothers, the adjusted odds ratios of postterm delivery for African Americans and Mexican Americans were 1.0 (0.5-3.2) and 1.0 (0.6-1.7), respectively.

We conclude that African Americans and Mexican Americans have greater postterm delivery rates than do Whites; however, commonly cited individual and community-level risk factors account for most of the disparity.