Racial Disparities in Maternal Exposure to Ambient Air Pollution During Pregnancy and Prevalence of Congenital Heart Defects.

Air pollution may be a potential cause of congenital heart defects (CHDs), but racial disparities in this association are unexplored. We conducted a statewide population-based cohort study using North Carolina birth data from 2003-2015 (N=1,225,285) to investigate the relationship between air pollution and CHDs (specifically pulmonary valve atresia/stenosis, Tetralogy of Fallot (TOF), and atrioventricular septal defect (AVSD)). Maternal exposure to particulate matter ≤2.5 micrometers in diameter (PM2.5) and ozone during weeks 3-9 of pregnancy were estimated using the Environmental Protection Agency's Downscaler Model. Single- and co-pollutant log-binomial models were created for the entire population and stratified by race to investigate disparities. Positive associations between PM2.5 and CHDs were observed. An increasing concentration-response association was found for PM2.5 and TOF in adjusted, co-pollutant models (Quartile 4 prevalence ratio: 1.46; 95% CI: 1.06, 2.03). Differences in the effect of PM2.5 on CHD prevalence were seen in some models stratified by race, although clear exposure-prevalence gradients were not evident. Positive associations were also seen in adjusted, co-pollutant models of ozone and AVSD. Study results suggest that prenatal PM2.5 and ozone exposure may increase the prevalence of certain CHDs. A consistent pattern of differences in association by race/ethnicity was not apparent.