Maternal exposure to ozone during pregnancy and risk of gestational diabetes in a Beijing pregnancy cohort study.

backgroundGestational diabetes mellitus (GDM) exerts profound and lasting impacts on both maternal and offspring health, and the prevalence of GDM has been increasing. Several studies have demonstrated a close association between air pollution and GDM. Ozone, recognized as an emerging contaminant, has exhibited a rising trajectory in exposure levels over the past few years. While ozone exposure levels are rising, studies have reported inconsistent findings regarding its association with the risk of GDM. More importantly, identifying possible exposure windows is essential for informing targeted prenatal protection and population‑level preventive strategies, yet such evidence for O₃ remains limited.

objectivesTo investigate the association between prenatal ozone exposure and the risk of GDM among pregnant women in Northern Chinese cities, and to identify critical exposure windows.

methodsA total of 8,847pregnant women who received perinatal health care services from January 2020 to June 2024 were included in this study. GDM was diagnosed by the examination of oral glucose tolerance test (OGTT) between 24 and 28 gestation weeks. Two time windows were estimated as gestation0-13+ 6 weeks, and gestation14-23+ 6 weeks. Multiple logistic regression and Restricted cubic splines were used to ascertain whether the association between GDM and O3 is linear. The Generalized Linear Model (GLM) was employed to identify the potential exposure time windows.

results2,185 women were diagnosed with GDM in 8,847 pregnant women in this research. A significant positive linear association between O3 and GDM was found specifically during weeks 0–23+ 6 of gestation, with no evidence of a nonlinear relationship or a specific safety threshold. After adjusting for other pollutants, the significant association between O₃ exposure and GDM persisted across the entire exposure period (0–23⁺⁶ weeks). Gestational weeks 0–13⁺⁶ were identified as a critical window of susceptibility for GDM. Notably, significant associations between O₃ exposure and Postprandial Glucose 1 h(1hPG) and Postprandial Glucose 2 h(2hPG) levels were exclusively observed during 14–23⁺⁶ weeks of gestation.

conclusionThis study found that gestational O₃ exposure disrupts glucose homeostasis and increases the risk of GDM. Furthermore, 0–13⁺⁶ weeks of gestation were identified as a possible window for the effects of O₃ exposure on GDM. Weeks 14–23⁺⁶ of gestation were identified as a period of increased susceptibility for the effects of O₃ exposure on 1hPG and 2hPG.