Methods Based on the data from Shanghai birth registry system from 2008 to 2012 and the daily air pollution records of PM10, SO2, and NO2 from 2007 to 2012 from Shanghai Environmental Monitoring Center, a retrospective cohort study involving 964.3 thousand newborns was conducted to calculate individual level of maternal exposure to selected air pollutants during the second trimester by gestation week and delivery date. Influencing factors of birth weight were identified through comparing the demographic characteristics of infants and mothers, and the association between air pollutant exposure in the second trimester and birth weight was assessed by multiple linear regression analysis.
Results Maternal exposure to the studied three pollutants in the second trimester showed negative effects on birth weight. According to the one-pollutant models, the birth weight was reduced by 4.4 g and 1.1 g for each 10 μg/m3 increase of PM10 and SO2, respectively. According to the two-pollutant models, the impact of PM10 combined with either SO2 or NO2 on birth weight was greater than PM10 alone. According to the three-pollutant model, birth weight was reduced by 20.7 g for each 10 μg/m3 increase of PM10, and 3.5 g for each 10 μg/m3 increase of SO2.
Conclusion Maternal air pollutant exposure in the second trimester is associated with birth weight. The impact of air pollution on pregnancy outcomes should be concerned.
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