Exposure to ambient fine particulate matter during pregnancy and gestational weight gain

Gestational weight gain (GWG) is increasingly reported to be associated with adverse birth outcomes. However, the effect of PM_2.5 exposure during pregnancy on GWG is unknown.

We investigated the associations between the exposure to PM_2.5 and GWGs during three pregnancy trimesters based on a prospective birth cohort.

Data were obtained from 2029 pregnant women who participated in a birth cohort between January 2013 and October 2014 in Wuhan, China. A spatial-temporal land use regression model was used to estimate the trimester and overall pregnancy exposures of PM_2.5 of each pregnant woman. The relationships between PM_2.5 exposure and GWG were estimated using linear mixed models.

The median value of GWG was 2.0 kg (interquartile range (IQR): 4.0) in the first trimester, 6.5 kg (IQR: 3.5) in the second trimester, and 7.0 kg (IQR: 3.5) in the third trimester, respectively. The exposure to PM_2.5 was peaked in the first trimester (median concentration: 117.3 μg/m³ (IQR: 71.9)). After adjustment for potential confounders, each 10 μg/m³ increase in PM_2.5 was consistently associated with increases in GWG in overall pregnancy (0.14 kg, 95% confidence interval (CI): 0.12, 0.17), the first (0.15 kg, 95%CI: 0.12, 0.18), second (0.15 kg, 95%CI: 0.10, 0.19) and third trimester (0.13 kg, 95%CI: 0.09, 0.17). Further stratified analysis indicated that pregnant women who delivered in spring or summer gained more body weight associated with PM_2.5 exposure.

This study provides evidence on the effect of exposure to PM_2.5 on GWG and it is the first report on the importance of reducing the ambient PM_2.5 in controlling of GWG in pregnant women.