Immigrant Disparities in Estimated Effects of Fine Particulate Matter on Birth Weight

Abstract

BACKGROUND AND AIM: Maternal exposure to fine particulate air pollution (PM2.5) during pregnancy has been linked to lower newborn birth weight, a risk factor for disease and mortality. As little is known about PM2.5 effect disparities by immigrant status (i.e., US-born vs. immigrant mother), we estimated PM2.5 associations with birth weight by immigrant status overall and within racial/ethnic groups. METHODS: For full-term live singletons in North Carolina from 2002 to 2014 (n = 1,082,485), we determined maternal exposure to PM2.5 during pregnancy using daily PM2.5 predictions from the EPA’s Fused Air Quality Surfaces Using Downscaling model. We estimated using regression the effect of PM2.5 on newborn birth weight, adjusted for maternal race, age, education, smoking, marital status, newborn prenatal care, and mode of delivery. RESULTS:Immigrant mothers had higher average exposure to PM2.5 than US-born mothers (12.1 μg/m³ vs. 11.7 μg/m³). Overall, newborns were 2.33 (95% confidence interval (CI): 0.49, 4.18) grams lighter per interquartile range (IQR) increment in PM2.5 (4.05 μg/m³). Estimated PM2.5 effects on birth weight were modified by maternal immigrant status (p = 0.02). Those with US-born mothers were 3.15 (95% CI: 1.12, 5.19) grams lighter per PM2.5 IQR while those with immigrant mothers were 4.88 (95% CI: 0.48, 9.27) grams heavier. Within racial/ethnic groups, we found similar patterns of disparities. Among non-Hispanic Blacks, those with US-born mothers were 4.47 (95% CI: 0.20, 8.74) grams lighter per PM2.5 IQR while those with immigrant mothers were 19.20 (95% CI: 2.03, 36.36) grams heavier. Disparities among those born to non-Hispanic White or Hispanic mothers were smaller in magnitude and not statistically different at the p = 0.05 level. Sensitivity analyses with the outcome small for gestational age showed similar patterns in disparities. CONCLUSIONS:Our study revealed disparities in associations between maternal exposure to PM2.5 during pregnancy and newborn birth weight by immigrant status. KEYWORDS: Particulate matter, Environmental disparities, Birth outcomes, Environmental justice, Immigrant health