Maternal Exposure to Air Pollution and Fetal Growth: Comparison of Three Exposure Modelling Approaches

Maternal air pollution exposure has been associated with impaired fetal growth, yet most studies have overlooked microenvironmental and personal exposures.

To examine associations between maternal air pollution exposure in key microenvironments (home, workplace, and commuting route) and fetal growth (birth weight and small for gestational age) using three modelling approaches and personal, home-indoor, and home-outdoor monitoring.

We used data from 1024 pregnant women in the Barcelona Life Study Cohort (2018-2021). Exposure to nitrogen dioxide, black carbon, and fine particulate matter (PM2.5) and its metallic constituents (copper, iron, and zinc) in each microenvironment were estimated using land use regression models, dispersion models, and hybrid land use regression-dispersion models, and combined with time-activity data to estimate total microenvironment exposures. Personal, home-indoor, and home-outdoor nitrogen dioxide concentrations were measured using passive samplers. Associations with birth weight and small for gestational age were evaluated using linear and logistic mixed-effects models.

Higher nitrogen dioxide and black carbon exposure at home and in total microenvironments, estimated by land use regression, dispersion, and hybrid models, were associated with lower birth weight. Increased black carbon exposure in the workplace (hybrid model) and PM2.5 exposure both at home (land use regression model) and in total microenvironments (land use regression and dispersion models) were also associated with reduced birth weight, as were higher home, workplace, and total microenvironmental exposure to metallic components of PM2.5 in land use regression models, although higher workplace PM2.5-zinc was associated with higher birth weight in hybrid models. Higher personal and home-outdoor nitrogen dioxide exposure were further associated with reduced birth weight. Similar patterns were observed for small for gestational age.

Maternal air pollution exposure was associated with impaired fetal growth. Home-based exposure estimates and short-term nitrogen dioxide measurements may serve as practical exposure proxies during pregnancy.