Seasonal Analyses of the Association between Prenatal Ambient Air Pollution Exposure and Abnormal Birth Weight in Guangzhou, China

摘要

Ambient air pollution has been linked to small for gestational age (SGA). However, the relationship between air pollution and large for gestational age (LGA) is unclear and very few study has investigated seasonal impact on the association between air pollution and SGA/LGA. Using data from the Guangzhou Birth Registry including 506,000 singleton live births between January 2015 and July 2017, we examined associations between ambient air pollutants and risk of SGA/ LGA, and whether the association varied by season. Daily average concentrations of PM2.5, PM10, N02, S02, and 03 from 11 monitoring stations were used to estimate district-specific exposures for each participant based on residential addresses during pregnancy. Two-level binary logistic regression models were used to evaluate associations between air pollution and SGA/LGA, controlling for temperature, seasonality, and individual covariates. Stratified analyses by season were performed to assess the modification of season on effects of air pollution. Exposure to PM2.5, N02, S02, and 03 was associated with increased risk of SGA, especially for exposure during late pregnancy. Stronger effects were observed for N02 and 03. For an IQR increase in exposure to N02 (12.7 ug/m3) or 03 (21.3 ug/m3) during the entire pregnancy, SGA risk increased by 8% (OR=1.08, 95% CI: 1.04-1.12) and 13% (OR=1.13, 95% CI: 1.10-1.15), respectively. When examined by season, significant associations between air pollutants and SGA were observed for women who conceived during summer or fall, and the patterns were consistent for all pollutants. Exposure to N02 during the entire pregnancy increased the risk of LGA (OR=1.05, 95%CI: 1.03-1.08), however, exposure to other pollutants was associated with reduced risk of LGA. Our results suggest that conception during different season might modify the association between ambient air pollution and SGA. The novel finding that N02 exposure increases the risk of LGA warrants further investigation.