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

Background: 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.

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

Methods: 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.

Results: 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.

Conclusions: 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.