Gestational diabetes mellitus and air pollution in the urban environment: Critical time windows of exposure across age and BMI classes

This exploratory study was designed to identify potential time windows of exposure to air pollution before and during early pregnancy that are more likely to be associated with GDM across age and body mass index (BMI) classes. The studied women were living in the urban region of Dijon (France) and delivered between 2005 and 2009. Data were obtained from medical records. Outdoor NO 2 and PM 1 0 cumulative home exposures were modelled over sliding 4-week exposure windows from 7 months before the last menstrual period to the 24th week of gestation. Logistic regression models estimating the odds ratio (OR) for GDM per 10 μg/m 3 increase in pollutant concentrations were applied to two age classes and four prepregnancy BMI classes. Among the 5218 women, 311 women under 35 years of age and 136 women over 35 years old developed GDM. The number of women who developed GDM in the underweight, normal weight, overweight and obese classes was 21 (6.1 %), 251 (7.4 %), 96 (10.6 %) and 65 (25.3 %), respectively. When considering PM 10 exposure, ORs of up to 2.03 were observed in women under 35 years of age. The highest ORs were associated with the [-09; −06], [-13; −10] and [-15; −12] windows in underweight, overweight, and obese women, respectively. The ORs were nearly all centred on one for NO 2 . For women living in an urban environment, our results suggest that critical 4-week windows of exposure to air pollution in both the pre- and postconception periods are associated with the development of GDM. • We used an iterative method to explore the air pollution-GDM relationship. • We highlight pre-conceptional critical windows of exposure to particles. • The potential critical windows could be modulated by age and BMI of mothers. • Our findings help strengthen women's health promotion in an urban environment.