# Associations Between Air Pollution Exposure and Gestational Weight Gain Pattern: Evidence from a Large-Scale Hospital-Based Retrospective Cohort Study

## TL;DR

This study shows that exposure to air pollution during pregnancy is linked to abnormal weight gain patterns, even at low concentrations.

## Contribution

The study provides evidence that low-level, long-term air pollution exposure during pregnancy affects gestational weight gain.

## Key findings

- Exposure to CO, NO2, PM10, PM2.5, and SO2 during pregnancy is positively associated with excessive gestational weight gain.
- O3 exposure is inversely associated with excessive gestational weight gain.
- The association between air pollution and gestational weight gain is stronger in women with higher pre-pregnancy BMI and older age.

## Abstract

Air pollution has been associated with dysregulated metabolism. However, evidence linking prenatal air pollution exposure to gestational weight gain (GWG) pattern remains limited. This retrospective cohort study of 47,793 pregnant women in Guiyang (2013–2022) assessed associations between air pollutants and GWG pattern. Positive associations were observed between excessive GWG and CO (per 1 μg/m3 increase), NO2, O3, PM10, PM2.5, and SO2 (per 10 μg/m3 increase) throughout the whole pregnancy period. Specifically, early-pregnancy exposure to CO (OR = 1.377, 95% CI: 1.201, 1.578) and NO2 (OR = 1.098, 95% CI: 1.068, 1.130), along with exposure to PM10 (OR = 1.058, 95% CI: 1.043, 1.073), PM2.5 (OR = 1.095, 95% CI: 1.073, 1.118), and SO2 (OR = 1.135, 95% CI: 1.102, 1.169) during late pregnancy significantly increased excessive GWG risk. Conversely, O3 exposure was inversely associated with excessive GWG. For insufficient GWG, only early-pregnancy exposures to PM10 (OR = 1.016, 95% CI: 1.001, 1.032), PM2.5 (OR = 1.022, 95% CI: 1.001, 1.043), and SO2 (OR = 1.031, 95% CI: 1.004, 1.058) showed significant positive associations. Furthermore, the restricted cubic spline (RCS) model revealed a nonlinear relationship between pollutant exposure and the risk of excessive GWG. Stratified analyses revealed that the air pollution and GWG (continuous) association was stronger among women with pre-pregnancy BMI ≥ 24 kg/m2 and aged ≥ 30 years. This study confirms that, even at lower concentrations, exposure to air pollutants during pregnancy is significantly associated with an increased risk of abnormal GWG. Compared to previous studies focusing on high-concentration areas, this finding provides additional evidence for assessing the health risks of air pollution exposure during pregnancy, suggesting that the potential metabolic effects of low-level, long-term exposure should be considered when developing maternal health strategies.