Racial and ethnic disparities in adverse birth outcomes: Differences by racial residential segregation

Abstract

Racial and ethnic disparities in adverse birth outcomes have persistently been wide and may be explained by individual and area-level factors. Our primary objective was to determine if county-level black-white segregation modified the association between maternal race/ethnicity and adverse birth outcomes using birth records from the National Center for Health Statistics (2012). Based on maternal residence at birth, county-level black-white racial residential segregation was calculated along five dimensions of segregation: evenness, exposure, concentration, centralization, and clustering. We conducted a two-stage analysis: (1) county-specific logistic regression to determine whether maternal race and ethnicity were associated with preterm birth and term low birth weight; and (2) Bayesian meta-analyses to determine if segregation moderated these associations. We found greater black-white and Hispanic-white disparities in preterm birth in racially isolated counties (exposure) relative to non-isolated counties. We found reduced Hispanic-white disparities in term low birth weight in racially concentrated and centralized counties relative to non-segregated counties. Area-level poverty explained most of the moderating effect of segregation on disparities in adverse birth outcomes, suggesting that area-level poverty is a mediator of these associations. Segregation appears to modify racial/ethnic disparities in adverse birth outcomes. Therefore, policy interventions that reduce black-white racial isolation, or buffer the poor social and economic correlates of segregation, may help to reduce disparities in preterm birth and term low birth weight.

Keywords: Bayesian meta-analysis; CrI, credible interval; Health disparities; OR, odds ratio; Preterm birth; Racial residential segregation; SD, standard deviation; Term low birth weight.

Fig. 1

Distribution of the proportion of black individuals for segregated and non-segregated counties for each dimension of segregation, United States, 2012. For evenness, the difference between the percent of the population that is black at the census tract and county level is shown. Values above zero indicate the percent of the population that is black at the census tract level is greater than the percent of the population that is black at the county level. For the other dimensions of segregation, the distribution of the percent of the population that is black at the census tract level is shown. The level of segregation for each county appears in parentheses. Data were obtained from 2012, 5-year estimates from the American Community Survey.

Fig. 2

County-specific posterior mean odds ratios and highest posterior density 95% credible intervals for black compared to white women for preterm birth by level of segregation, United States, 2012 Panel A is evenness, panel B is exposure, panel C is concentration, and panel D is centralization. An asterisk indicates that the 95% credible interval for the posterior mean odds ratio multiplier for segregated relative to non-segregated counties excludes 1. Dots represent county-specific posterior mean odds ratios and horizontal lines represent highest posterior density 95% credible intervals. Vertical lines indicate mean odds ratios for segregated counties (solid line), mean odds ratios for non-segregated counties (dotted line), and odds ratio of 1 (dashed line).