Associations between artificial light exposure during pregnancy and the risk of gestational diabetes mellitus: a prospective cohort study

Background: Gestational diabetes mellitus (GDM), characterized by glucose intolerance first identified during pregnancy, poses significant risks to both maternal and neonatal health. With its prevalence rising globally, GDM has become a critical public health issue. Emerging evidence suggests that environmental factors, such as light exposure, may influence GDM risk. Objective: This study aimed to investigate the associations between exposure to electronic device screen time, indoor and outdoor light during pregnancy, and the risk of developing GDM, providing new insights for GDM prevention and management. Methods: A prospective cohort study was conducted, enrolling 1,030 pregnant women from five hospitals in Fujian, China, between January and July 2025. Baseline data were collected during the first and second trimesters, and participants were followed until 24-28 weeks of gestation for GDM diagnosis. Multivariate logistic regression was used to assess associations, and dose-response relationships were analyzed. Results: Among the participants, 180 (17.48%) were diagnosed with GDM. The adjusted multivariate model revealed that both longer indoor light exposure and total electronic device use time were significant independent risk factors for GDM. Dose-response analysis indicated a significant increase in risk when daily electronic device use and indoor light exposure exceeded 3 hours, with a significant synergistic interaction between the two. In contrast, the use of outdoor protective measures demonstrated a strong protective effect. Conclusion: Indoor artificial light exposure and electronic device use are significant independent risk factors for GDM, demonstrating clear dose-response relationships and a synergistic effect. Outdoor protective measures can effectively reduce GDM risk. These findings suggest that reducing prolonged screen time and indoor artificial light exposure, as well as adopting outdoor protective measures, may be associated with lower odds of GDM. Intervention studies are needed to evaluate whether modifying these exposures can reduce GDM incidence. Future research should focus on elucidating the underlying biological mechanisms and validating the effectiveness of interventional strategies.