Prenatal exposure to air pollutant mixtures and birthweight in the upstate KIDS cohort

Abstract

BackgroundSingle-pollutant models have linked prenatal PM2.5 exposure to lower birthweight. However, analyzing air pollutant mixtures better captures pollutant interactions and total effects. Unfortunately, strong correlations between pollutants restrict traditional methods. ObjectivesWe explored the association between exposure to a mixture of air pollutants during different gestational age windows of pregnancy and birthweight. MethodsWe included 4,635 mother-infant dyads from a New York State birth cohort born 2008–2010. Air pollution data were sourced from the EPA’s Community Multiscale Air Quality model and matched to the census tract centroid of each maternal home address. Birthweight and gestational age were extracted from vital records. We applied linear regression to study the association between prenatal exposure to PM2.5, PM10, NOX, SO2, and CO and birthweight during six sensitive windows. We then utilized Bayesian kernel machine regression to examine the non-linear effects and interactions within this five-pollutant mixture. Final models adjusted for maternal socio-demographics, infant characteristics, and seasonality. ResultsSingle-pollutant linear regression models indicated that most pollutants were associated with a decrement in birthweight, specifically during the two-week window before birth. An interquartile range increase in PM2.5 exposure (IQR: 3.3 µg/m3) from the median during this window correlated with a 34 g decrement in birthweight (95 % CI: −54, −14), followed by SO2 (IQR: 2.0 ppb; β: −31), PM10 (IQR: 4.6 µg/m3; β: −29), CO (IQR: 60.8 ppb; β: −27), and NOX (IQR: 7.9 ppb; β: −26). Multi-pollutant BKMR models revealed that PM2.5, NOX, and CO exposure were negatively and non-linearly linked with birthweight. As the five-pollutant mixture increased, birthweight decreased until the median level of exposure. DiscussionPrenatal exposure to air pollutants, notably PM2.5, during the final two weeks of pregnancy may negatively impact birthweight. The non-linear relationships between air pollution and birthweight highlight the importance of studying pollutant mixtures and their interactions.