Influence of socioeconomic factors and race on birth outcomes in urban Milwaukee.

PURPOSE A national study found that infants born in low socioeconomic areas had the worst infant mortality rates (IMRs) and the highest racial disparity. Racial disparities in birth outcomes are also evident in the city of Milwaukee, with African American infants at 3 times greater the risk than white infants. This study was conducted to examine the influence of socioeconomic status (SES) and race on birth outcomes in the city of Milwaukee. METHODS Milwaukee ZIP codes were stratified into lower, middle, and upper SES groups. IMR, low birth weight, and preterm birth rates by race were analyzed by SES group for the years 2003 to 2007. RESULTS The overall IMR for the lower, middle, and upper SES groups were 12.4, 10.7, and 7.7, respectively. The largest racial disparity in IMR (3.1) was in the middle SES group, versus lower (1.6) and upper (1.8) SES groups. The overall percent of low birth weight infants for the lower, middle, and upper SES groups was 10.9%, 9.5%, and 7.5%, respectively. Racial disparity ratios in low birth weight were 2.0, 1.9, and 1.9 for lower, middle and upper SES groups. The overall percent of preterm birth was 15.4%, 13.2%, and 10.6% of births within the lower, middle, and upper SES groups, respectively, with a disparity ratio of 1.6 across all SES groups. CONCLUSIONS For all outcomes, African American infants born in the upper SES group fared the same or worse than white infants born in the lower SES group. Although higher SES appeared to have a protective effect for whites in Milwaukee, it did not have the same protective effect for African Americans.