Decomposition Analysis of Black–White Disparities in Birth Outcomes: The Relative Contribution of Air Pollution and Social Factors in California

Abstract

Background:Racial/ethnic disparities in preterm birth (PTB) are well documented in the epidemiological literature, but little is known about the relative contribution of different social and environmental determinants of such disparities in birth outcome. Furthermore, increased focus has recently turned toward modifiable aspects of the environment, including physical characteristics, such as neighborhood air pollution, to reduce disparities in birth outcomes.Objectives:To apply decomposition methods to understand disparities in preterm birth (PTB) prevalence between births of non-Hispanic black individuals and births of non-Hispanic white individuals in California, according to individual demographics, neighborhood socioeconomic environment, and neighborhood air pollution.Methods:We used all live singleton births in California spanning 2005 to 2010 and estimated PTBs and other adverse birth outcomes for infants borne by non-Hispanic black mothers and white mothers. To compare individual-level, neighborhood-level, and air pollution [Particulate Matter, 2.5 micrometers or less (PM2.5) and nitrogen dioxide (NO2)] predictors, we conducted a nonlinear extension of the Blinder–Oaxaca method to decompose racial/ethnic disparities in PTB.Results:The predicted differences in probability of PTB between black and white infants was 0.056 (95% CI: 0.054, 0.058). All included predictors explained 37.8% of the black–white disparity. Overall, individual (17.5% for PTB) and neighborhood-level variables (16.1% for PTB) explained a greater proportion of the black–white difference in birth outcomes than air pollution (5.7% for PTB).Conclusions:Our results suggest that, although the role of individual and neighborhood factors remains prevailing in explaining black–white differences in birth outcomes, the individual contribution of PM2.5 is comparable in magnitude to any single individual- or neighborhood-level factor. https://doi.org/10.1289/EHP490

Black–White Disparities in Preterm Birth: Geographic, Social, and Health Determinants

“…Racial and economic segregation may be better studied at more granular levels not available in national vital records. 20,46 Unlike other studies, this study demonstrated that the contribution of sociodemographic factors to the disparity in PTB may operate through more proximal maternal health characteristics. The findings show a sizable black −white disparity in hypertension during pregnancy, specifically chronic hypertension (Table 1).…”

“…7 This reduction in explanatory power for VPTB is consistent with other analyses. 20,34 The study findings support the role of social determinants in driving a large portion of the black−white disparity in PTB and VPTB. The importance of education on health is well established, 35,36 and maternal education was found to be a meaningful contributor to PTB disparities in the present analyses.…”

“…19 Finally, a California-based study attributed 38% of the black−white PTB disparity to maternal, neighborhood socioeconomic, and environmental factors but did not include proximate healthcare or health status information. 20 Building upon and combining the strengths of these previous studies, the authors investigate the detailed contribution of geographic, sociodemographic, and health indicators to black−white differences in PTB and VPTB using national birth data for all 50 states and the District of Columbia. This study uses more timely data to extend these prior studies by examining newly available variables, such as interpregnancy interval, and validated measures of residential segregation.…”

Retirements of Coal and Oil Power Plants in California: Association With Reduced Preterm Birth Among Populations Nearby

“…In California, there are racial disparities in preterm birth; non-Hispanic black women have nearly double the prevalence of preterm birth of non-Hispanic white women (18). Despite calls in the environmental health literature (19), limited research has explored the modifying role of individual-level race/ethnicity and socioeconomic status in the relationship between air pollution and preterm birth (20)(21)(22), and none has done so in relation to point sources of pollution like power plants.…”

Regional variation in Black infant mortality: The contribution of contextual factors

“…Previous studies have focused on the sources of the Black-White disparity [2][3][4][5], which can be lower by virtue of high White versus low Black IMR [6], and limited in the provision of Black-specific contextual information as they are often dominated by the characteristics of the larger White community [5]. Studies that have examined Black infant mortality either alone or in addition to White infant mortality have suggested associations with various contextual factors within social, economic, environmental, and health domains but none have examined their contribution to regional variation [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Moreover, several studies have shown that the predictors of Black IMR are different than those of White IMR, and thus support a priority focus on the higher Black IMR [2,4,23,24].…”