Objective:Gestational diabetes mellitus(GDM),a common complication of pregnancy,is an important factor affecting maternal health and offspring development,and can have far-reaching effects on the mother and her offspring.In recent years,economic development,coupled with lifestyle changes,has led to a dramatic increase in the incidence of GDM,placing a huge burden on the global health economy and healthcare system.According to the International Diabetes Federation(IDF),the global prevalence of GDM will be about 14.0%in 2021.Several provinces and regions in China have also carried out analysis of the current situation of GDM incidence,and it was found that there is some variability in the incidence of GDM among localities.Chongqing is a mega city and municipality directly under the central government in China,with a resident population of more than 30 million,and there is no basic data on the incidence of GDM in Chongqing.Therefore,there is an urgent need to conduct a situational analysis of GDM incidence in Chongqing to identify the risk factors affecting GDM and provide a scientific basis for early prevention,screening and management of GDM in Chongqing.Our team has worked on the effects of environmental pollutant exposure on reproductive health for many years,and in previous studies we have found that air pollution causes damage to male reproductive health and that air pollutant exposure is also a risk factor for GDM.Clinical studies have found different metabolic profiles and specificity of beta-cell defects in fasting and postprandial hyperglycemia.Previous studies have evaluated the association between maternal exposure to air pollution and blood glucose at different time points of the oral glucose tolerance test(OGTT).However,few studies have examined the effects of maternal air pollutant exposure on different subtypes of GDM,and the critical time window for the occurrence of GDM by air pollution exposure is unclear.Therefore,this study further investigated the association between periconceptional air pollution exposure and the risk of GDM and the critical time window for periconceptional air pollutant exposure,and distinguished the susceptibility of three different GDM subtypes to air pollution exposure.Methods:1.This study was analyzed by recruiting 23,896 pregnant women who underwent prenatal checkups at Chongqing Maternal and Child Health Hospital from 2018to 2021 and completed OGTT screening at our hospital at weeks 24-28 of gestation.General demographic information and risk factor exposure of pregnant women were investigated.The mean incidence of GDM in different years and regions was counted using descriptive analysis,and the correlation between different risk factors and the incidence of GDM was analyzed using univariate and multifactor logistic regression models.2.In the first part of the study population,7,593 pregnant women with missing data on individual air pollution exposure were excluded,resulting in the inclusion of 16,303 pregnant women for retrospective analysis.The average daily exposure levels of individual air pollution(including PM2.5,PM10,O3,NO2,SO2,and CO)were evaluated by using a machine learning algorithm.The mean concentrations of air pollution exposure were also assessed for pre-pregnancy,early pregnancy,mid-pregnancy,and 12 weeks before and 24 weeks after the last menstrual period.The association between air pollutant exposure and risk of GDM and each subgroup was analyzed using a single-pollutant model and a two-pollutant logistic regression model.Distributed lagged nonlinear models(DLNMs)were further used to assess the critical time windows for the occurrence of air pollution exposure and GDM risk at different gestational weeks.Finally,stratified analyses were performed according to maternal age,body mass index(BMI)in early pregnancy and OGTT sampling season,and likelihood ratio tests were used to calculate interaction P values.Results:1.A total of 23,869 pregnant women from Chongqing were included in this study,including 21,850(91.4%)from the main city and 2,046(8.6%)from the non-main city of Chongqing.There were 6,269 patients(26.2%)diagnosed with GDM,and the annual incidence of GDM was 27.3%,25.0%,26.4%,and 26.4%from 2018-2021,respectively,while there were some differences in the incidence of GDM among districts,with the highest incidence of GDM in Beibei district(30.9%)and the lowest incidence in Jiulongpo district(23.9%).Multifactorial logistic regression results showed that after adjusting for covariates,age(OR=1.89,95%CI:1.75~2.05,P<0.001),early pregnancy BMI(OR=2.36,95%CI:2.16~2.58,P<0.001),smoking history(OR=1.31,95%CI:1.05~1.63,P=0.019),history of endocrine disorders(OR=10.47,95%CI:9.70~11.30,P<0.001)and multiple pregnancies(OR=1.28,95%CI:1.05~1.55,P=0.015)were risk factors for GDM.2.By analyzing 16,303 pregnant women in Chongqing,2,482(15.2%)of all pregnant women were diagnosed with GDM,including 214 with isolated fasting hyperglycemia(GDM-IFH),1,692 with isolated post-load hyperglycemia(GDM-IPH)and284 with combined hyperglycemia(GDM-CH).First,the association between air pollutants and the risk of GDM and each subgroup was analyzed using logistic regression models for single pollutant exposure.The results of the study showed that PM10 and PM2.5exposure in early pregnancy was associated with GDM(PM10:OR=1.19,95%CI:1.07~1.33;PM2.5:OR=1.32,95%CI:1.15~1.50)and GDM-IPH(PM10:OR=1.23,95%CI:1.09~1.39;PM2.5:OR=1.38,95%CI:1.18~1.61)were positively associated with the risk of GDM.Mid-pregnancy O3 exposure was positively associated with the risk of GDM(OR=1.43,95%CI:1.15~1.79).Significant associations of PM10 and PM2.5 exposure in early pregnancy and O3 exposure in mid-pregnancy with the risk of GDM and GDM-IPH were also observed in a two-pollutant model.In addition,CO exposure in pre-pregnancy and early pregnancy was also positively associated with the risk of GDM and GDM-IPH.The results of the distributed lag nonlinear models showed that the sensitive time windows for PM10,PM2.5,and O3 exposure were weeks 15-20,16-27,and 31-36,respectively.Stratification according to OGTT sampling season,age and early pregnancy BMI showed a greater association between air pollutants and risk of GDM and GDM-IPH in warm season,normal weight or lean pregnant women,while no significant differences were observed in different age groups.OGTT sampling season and early pregnancy BMI interact with air pollution exposure on GDM and risk for each subgroup.Conclusions:1.The prevalence of GDM among women of reproductive age in Chongqing is at a high level in 2018-2021,and maternal age,early pregnancy BMI,history of smoking,history of endocrine diseases and multiple pregnancies are significantly associated with the risk of developing GDM.2.Maternal exposure to PM10 and PM2.5 in early pregnancy and O3 in mid-pregnancy increased the risk of GDM and GDM-IPH,and GDM-IPH was the susceptible subtype of pollutant exposure.The sensitive time windows for PM10,PM2.5,and O3,exposure were weeks 15-20,16-27,and 31-36,respectively. |