Early pregnancy particulate matter exposure, pre-pregnancy adiposity and risk of gestational diabetes mellitus in Finnish primiparous women: An observational cohort study

To evaluate the association between the exposure of particulate matter with an aerodynamic diameter of ≤ 2.5μm (PM2.5) and with an aerodynamic diameter of ≤ 10μm (PM10) over the first trimester and the risk of gestational diabetes mellitus (GDM), and to assess whether maternal pre-pregnancy body mass index (BMI) modified the GDM risk. All Finnish primiparous women without previously diagnosed diabetes who delivered between 2009 and 2015 in the city of Vantaa, Finland, composed the study cohort (N = 6189). Diagnosis of GDM was based on a standard 75 g 2-hour oral glucose tolerance test. The average daily concentration of PM2.5 and PM10 over the first trimester was calculated individually for each woman. The relationship between exposure of PM2.5 and PM10 and GDM was analyzed with logistic models. No association was observed between the average daily concentrations of PM2.5 and PM10 over the first trimester and the GDM risk. When simultaneously taking BMI and PM10 into account both mean daily PM10 concentration (p = 0.047) and pre-pregnancy BMI (p = 0.016) increased GDM risk independently and an interaction (p = 0.013) was observed between PM10 concentration and pre-pregnancy BMI. Even globally low PM10 exposure level together with elevated maternal pre-pregnancy BMI seems to increase the GDM risk. •In a high-income European area mean daily concentrations of PM are low.•Early pregnancy exposure of PM and risk for GDM showed no association.•Increasing pre-pregnancy BMI and increasing exposure of PM10 increase GDM risk.