Joint Mixture Associations of Prenatal Air Pollution and Polyunsaturated Fatty Acid Intake on Birth Weight Outcomes in an African American Cohort

Dietary polyunsaturated fatty acids (PUFAs) play a critical role in healthy pregnancy by supporting fetal development and modulating inflammation. Few studies have considered how dietary PUFAs and environmental exposures may jointly influence birth outcomes. We therefore investigated the joint mixture associations of prenatal exposure to traffic-related air pollutants (TRAPs), including carbon monoxide, fine particulate matter (PM2.5), nitrogen oxides, and dietary PUFA intake, on birth weight for gestational age z-score (BWZ) in 297 pregnant African Americans enrolled in the Atlanta Maternal-Child Cohort. At mean α-linolenic acid (ALA) intake, a first-trimester interquartile range (IQR) increase in PM2.5 was associated with a 0.08 (95% CI: 0.02–0.18) unit decrease in BWZ, but at twice the mean ALA intake, the same PM2.5 increase was associated with a 1.12 (95% CI: 0.19–2.05) unit increase in BWZ (p-int = 0.04). Similarly, at mean linoleic acid (LA) intake, a first-trimester IQR increase in PM2.5 was associated with a 0.08 (95% CI: 0.02–0.17) unit decrease in BWZ, whereas at twice the mean LA intake, PM2.5 exposure was associated with a 1.09 (95% CI, 0.16–2.02) unit increase (p-int = 0.09). Our findings suggest that higher prenatal PUFA intake may mitigate the adverse effects of air pollution on fetal growth.