Maternal Exposure to Fine Particulate Matter and Its Chemical Components Increasing the Occurrence of Gestational Diabetes Mellitus in Pregnant Japanese Women

INTRODUCTION: PM(2.5) exposure is a suspected risk factor for diabetes. It is hypothesized that maternal PM(2.5) exposure contributes to the development of gestational diabetes mellitus (GDM). The association between PM(2.5) exposure and GDM is controversial and limited evidence is available for the exposure to PM(2.5) chemical components. We investigated the association between maternal exposure to total PM(2.5) mass and its components, particularly over the first trimester (early placentation period), and GDM. METHODS: Data were obtained from the Japan Perinatal Registry Network database, which includes all live births and stillbirths after 22 weeks of gestation at 39 cooperating hospitals in 23 Tokyo wards (2013-2015). At one fixed monitoring site, we performed daily filter sampling of fine particles and measured daily concentrations of carbon and ion components. The average concentrations of total PM(2.5) and its components over the 3 months before pregnancy and the first (0-13 gestational weeks) and second (14-27 gestational weeks) trimesters were calculated and assigned to each woman. We estimated the odds ratios (ORs) of GDM in a multilevel logistic regression model. RESULTS: Among 82,773 women (mean age at delivery = 33.7 years) who delivered singleton births, 3,953 (4.8%) had GDM. In the multiexposure period model, an association between total PM(2.5) exposure and GDM was observed for exposure over the first trimester (OR per interquartile range (IQR = 3.63 μg/m(3)) increase = 1.09; 95% confidence interval (CI) = 1.02-1.16), but not for the 3 months before pregnancy or the second trimester. For PM(2.5) components, only organic carbon exposure over the first trimester was positively associated with GDM (OR per IQR (0.51 μg/m(3)) increase = 1.10; 1.00-1.21). CONCLUSIONS: This is the first evidence that exposure to total PM(2.5) and one of its components, organic carbon, over the first trimester increases GDM occurrence in Japan.