Investigate The Relationship Between Exposure To Air Pollutants During Pregnancy And Adverse Pregnancy Outcomes In Urban Areas Of Chongqing By LUR Model

Objectives（1）Land use regression（LUR）models for predicting particulate matter with an aerodynamic diameter≤2.5 um(PM_2.5)and nitrogen dioxide（NO₂）concentrations in Chongqing were established to estimate the individual exposure of pregnant women.（2）To analyze the relationship between PM_2.5 and NO₂ exposure in the first trimester,second trimester,third trimester and the whole pregnancy with premature birth,gestational diabetes mellitus（GDM）,macrosomia and small for gestational age（SGA）.Methods（1）Based on the PM_2.5 and NO₂ monitoring data of 16 routine air quality monitoring sites in Chongqing in 2015,and the geographic information data of land use,roads,population,elevation,vegetation coverage around these monitoring sites,the LUR models of PM_2.5 and NO₂ were established by multiple stepwise regression method,and the models were verified by leave-one-out cross validation（LOOCV）.（2）The established LUR models for PM_2.5 and NO₂ were used to estimate the exposure level of each pregnant woman in the first trimester,second trimester,third trimester and the whole pregnancy according to the home address and time adjustment factors of pregnant women.Logistic regression was used to explore the relationship between the exposure of the two pollutants in different pregnancy periods and adverse pregnancy outcomes.Potential confounding factors coexposure to PM_2.5 and NO₂was investigated by two-pollutant models.Stratified analysis was used to explore the gender differences in the effects of pollutants on adverse pregnancy outcomes.Results（1）The variables PSTTM＿500m and Rural＿5000m were included in PM_2.5 LUR model.The coefficients of these two variables were 0.75×10^-3and-0.49×10^-1,respectively.The variables PSTTM＿500m and NDVI＿5000m were included in NO₂ LUR model.The coefficients of these two variables were 0.18×10^-2 and-0.38×10^-2,respectively.The variance inflation factors（VIF）of four variables were less than 3.The adjusted R² of PM_2.5 and NO₂ LUR models were 0.75 and 0.67,respectively.The R² of LOOCV were 0.59 and 0.57,and root mean square error（RMSE）were 1.71and 5.33,respectively.（2）Logistic regression analysis showed that the risk of SGA increased by 39%（odds ratio（OR）=1.39（1.03,1.87））for each increased interquartile range（IQR）in PM_2.5exposure in the second trimester of pregnancy.The risk of SGA increased by 42%（OR=1.42（1.06,1.95））for each increased IQR in NO₂ exposure in third trimester.In addition,we divided pregnant women into four groups according to the exposure level of each pregnancy period.Taking the lowest exposure group as the reference,we analyzed the association between the highest exposure group and SGA,and the results were consistent with the analysis results when the exposure variables were continuous variables:it also showed that PM_2.5 exposure in the second trimester and NO₂ exposure in the third trimester would increase the risk of SGA.The two-pollutant models also showed similar results.Gender stratification analysis showed that only in the male fetal subgroup,the exposure was significantly associated with SGA.The lowest exposure group as a reference,the risk of SGA in the highest PM_2.5 exposure group in the second trimester and the highest NO₂ exposure group in the third trimester significantly increased.No significant correlation was found between PM_2.5or/and NO₂ exposure during pregnancy and the adverse pregnancy outcomes of premature birth,GDM and macrosomia.Conclusions（1）The LUR model established in this study good prediction accuracy,and can be used for individual exposure estimation of pollutants,which could provide good model for epidemiological research on the relationship between PM_2.5 and NO₂exposure and health outcomes in Chongqing.（2）PM_2.5 or NO₂ exposure during pregnancy and were not associated with the adverse pregnancy outcomes of premature birth,GDM and macrosomia,but exposure of PM_2.5 in the second trimester and NO₂ in the third trimester was associated with the increased risk of SGA.The sex of fetus was an important factor influencing the association between air pollutant exposure and SGA during pregnancy.Male fetuses might be susceptible to PM_2.5 and NO₂ exposure.