Results: We found that air pollution exposure during pregnancy was positively associated with the risk of term
LBW. In the fully adjusted models, odds ratios following one interquartile range increase in each pollutant
were 1.09 (95% confidence interval: 1.00, 1.19) for suspended particulate matter (SPM), 1.11 (0.99, 1.26) for
nitrogen dioxide (NO2), and 1.71 (1.18, 2.46) for sulfur dioxide (SO2). Specifically, effect estimates for SPM and
NO2 exposure at the first trimester were higher than those at other trimesters, while SO2 was associated with
the risk at all trimesters. Nonsmoking mothers were more susceptible to SPM and NO2 exposure compared
with smoking mothers.