Environment/Climate Change
Prenatal Ambient Air Pollutant and Climatic Factors Mixture Exposure and Fetal Growth Stefania Papatheodorou* Stefania Papatheodorou Katie Senechal Michael Leung Anna Modest Michele Hacker Antonella Zanobetti
Introduction: Research linking prenatal ambient air pollution and climatic factors with fetal growth has largely considered one factor at a time. Real-life exposure involves exposure to mixtures of pollutants and climatic factors; not considering joint effects/effect modification by co-exposures contributes to misleading results.
Methods: We used ultrasound measures of biparietal diameter (BPD), head circumference, femur length, and abdominal circumference (AC), in addition to birth weight, from 9,446 pregnancies that were delivered at the Beth Israel Deaconess Medical Center from 2011-2016. Weekly prenatal pollutant exposures were estimated using satellite-based hybrid chemical-transport models, including nitrogen dioxide (NO2), ozone(O3), particulate matter (PM2.5), and high-resolution data for temperature and relative humidity. We examined associations between weekly-averaged prenatal pollution mixture levels and outcomes using Bayesian Kernel Machine Regression-Distributed Lag Models (BKMR-DLMs) to identify susceptibility windows for each component and estimate a potentially complex mixture exposure-response relationship including nonlinear effects and interactions. We adjusted for sociodemographic and clinical characteristics, seasonal and long-term trends, and area-level factors.
Results: BKMR-DLMs identified the stronger effect for temperature at early gestation predicting lower BPD in mid-pregnancy (up to -0.10 z-score (95% CI -0.16 to -0.04) at 16 to 23 weeks). There was a negative association between birthweight z-scores and exposure to mixtures of air pollutants, where up to −0.18 (95% CI -0.23 to -0.13) or approximately 88 g decrease in birthweight, comparing the 75th percentile to the median level of exposure to the air pollutant mixture could occur. There was evidence for interactions between O3, PM2 5, and temperature.
Conclusion: In this multi-pollutant model, we identified a strong association between exposure to higher temperature in early pregnancy and mid-pregnancy fetal brain measurements and a strong association between air pollutants and birthweight.
