Examining the Role of Race/Ethnicity in the Association between Air Pollution and Preterm Birth
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Gestational exposure to air pollution is associated with adverse pregnancy outcomes, including preterm birth (PTB), and these associations may differ across both individual- and area-level strata of race/ethnicity and poverty. We used a cohort (2006-2014) of North Carolina births combined with concentration estimates of ozone (O3) and fine particulate matter (PM2.5) from EPA’s Community Multi-scale Air Quality (CMAQ) model to estimate associations with PTB. Census tract-level data on race and poverty from the US Census Bureau’s 2009 and 2013 American Community Survey were used as stratification variables. Geocoded residential locations from birth records were linked to daily air pollutant estimates at the census tract centroids. PTB was associated with 1st and 2nd trimester O3 exposure [odds ratio (95% confidence interval) for an interquartile range increase: 1.09 (1.07, 1.10), 1.03 (1.02, 1.04), respectively]. When stratified by individual race and census-tract majority race, the odds of PTB associated with O3 in the 1st trimester was greater for non-Hispanic (NH) Black mothers living in majority NH non-Black census tracts [1.12 (1.08, 1.16)] compared to NH Black mothers living in majority NH Black census tracts [1.08 (1.05, 1.11)]. When stratified by individual-level socio-economic status (SES) and census tract-level SES indicators, odds of PTB associated with 1st trimester O3 exposure was greater for subjects with Medicaid living in census tracts with majority of residents under the poverty level [1.11 (1.06, 1.16)] compared to subjects without Medicaid living in the same census tracts [1.05 (1.03, 1.08)]. Odds of PTB associated with PM2.5 exposure were similar in both trimesters [1.07 (1.07, 1.08); 1.06 (1.05, 1.06)] and in stratified analyses. Air pollutant exposure is associated with increased odds of PTB; however, odds varies based on individual and neighborhood race and poverty indicators.