Association Of Early Pregnancy Exposure To Organic Pollutants And Gestational Diabetes Mellitus:A Nested Case-Control Study

【Objective】1.To assess plasma exposure levels of polycyclic aromatic hydrocarbons(PAHs),organochlorine pesticides(OCPs),polychlorinated biphenyls(PCBs)and polybrominated diphenyls(PBDEs)in the first trimesters of pregnancy.2.To analyze the association between exposure levels of organic pollutants(PAHs,OCPs,PCBs and PBDEs)in the first trimesters of pregnancy and the risk of gestational diabetes mellitus(GDM).3.To investigate the combined effects of exposure to multiple organic pollutants in the first trimesters of pregnancy on gestational diabetes mellitus(GDM).【Methods】In this study,a nested case-control study design within a prospective cohort was adopted,which is based on the Peking University Tongzhou Birth Cohort established in Tongzhou District Maternal and Child Health Hospital of Beijing.A total of 200 GDM patients who met the inclusion criteria and 200 normal blood glucose women withmatched with age(±2 years)and gestational age at taking oral glucose tolerance test(OGTT)were included for analysis.The plasma in the first trimester was collected,and the levels of PAHs and PCBs were detected by triple tandem quadrupole gas mass spectrometry,and OCPs and PBDES were detected by gas chromatography-mass spectrometry.Wilcoxon signed rank test for paired design was used to analyze the difference in the concentration of organic pollutants between the GDM group and the control group.Multivariate conditional Logistic regression model was used to analyze the association between organic pollutants and GDM.The KNN method was used to interpolate the early pregnancy physical activity intensity with a large number of variables missing(11.8%),and the sensitivity analysis of the interpolated variables was conducted.The association between organic pollutants and GDM was analyzed by grouping according to fetal sex.Bayesian kernel machine regression(BKMR)model was used to analyze the combined effects of organic pollutants on GDM.【Results】1.Compared with previous research,the exposure levels of PAHs,PCBs and PBDEs in this study population were lower,the exposure levels of HCB,Mirex and END in OCPs were higher,and the exposure levels of p,p’-DDE,p,p’-DDT were lower.2.There was no significant association between plasma exposure to PAHs in the first trimester and GDM,but the effects of FLU on GDM were different in fetal sex(heterogeneity test P value = 0.028).Among pregnant women who had male fetus,the FLU exposure was positive correlated with GDM on the numerical scale(OR = 3.16,95% CI: 0.80-12.40,P value = 0.099),Among pregnant women who had female fetus,the FLU exposure was negative correlated with GDM on the numerical scale(OR = 0.39,95% CI:0.11-1.38,P value = 0.143).3.The plasma END exposure levels in the first trimester pregnancy was devided into three categories.Compared with the lowest exposure groups,the risk of GDM had a1.84-fold increased(95%CI: 1.01-3.34)in the highest exposure groups,and a dose-response relationship was observed(linear trend test P value < 0.05).The association was independent of other important factors associated with GDM,including parity,maternal education,pre-pregnancy Body mass index(BMI),total daily calories in the first trimester,physical activity in the first trimester,and fetal sex.4.The median of plasma ∑OCPs in early pregnancy was used to compare the high exposure group and the low exposure group,and it was found that the higher exposure group had a 1.67-fold increased risk of GDM(95%CI: 1.02-2.75).The association was independent of other important influencing factors associated with GDM,including parity,maternal education,pre-pregnancy BMI,total daily calories in the first trimester,physical activity in the first trimester,and fetal sex.5.BKMR model were used to analyze combined effect.When considering the combined exposure of other OCPs,it was found that END was positively correlated with the occurrence risk of GDM(P value < 0.05),no statistically significant association was found between PAHs combined exposure and GDM(P value > 0.05),which is consistent with the results of single pollutant analysis.6.No significant associations were found between detected PCBs,PBDEs and GDM(P value > 0.05).【Conclusion】In this study,it was found that the exposure levels of PAHs,PCBs and PBDEs in the first trimester in Beijing area were relatively low,while the exposure levels of some OCPs were relatively high.END exposure in early pregnancy is associated with the risk of GDM,while other OCPs,PAHs,PCBs and PBDEs are not associated with the risk of GDM,which provides scientific evidence for further research on environmental risk factors of GDM.