COVID-19 lockdowns and gestational diabetes risk: trimester-specific exposure and stratified outcomes

Abstract Background The COVID-19 pandemic disrupted physical activity, nutrition, and stress, key determinants of gestational diabetes mellitus (GDM). We examined whether pandemic-period delivery and lockdown exposure were associated with GDM prevalence. Methods We conducted a historical cohort study at a tertiary medical center including singleton deliveries ≥ 24 weeks during April 2018–October 2019 (pre-pandemic) and April 2020–October 2021 (pandemic). The pandemic period encompassed three national lockdowns. The primary outcome was GDM diagnosed using standardized two-step screening. Secondary outcomes included cesarean delivery and macrosomia. Multivariable logistic regression adjusted for maternal age, pre-pregnancy BMI, parity, chronic hypertension, and pre-gestational diabetes. Trimester-specific lockdown exposure was assessed. Results Among 31,060 deliveries (15,190 pre-pandemic; 15,870 pandemic), GDM prevalence increased from 5.4% to 7.8% ( p < 0.001). After adjustment, the association remained significant (adjusted OR 1.29, 95% CI 1.12–1.49). First-trimester lockdown exposure showed the strongest association (adjusted OR 1.6, 95% CI 1.3–2.0). Despite rising GDM, cesarean delivery rates and macrosomia remained stable, though cesarean for suspected macrosomia increased (5.7% to 8.1%, p < 0.001). Mean gestational weight gain did not differ between periods. Conclusions Pandemic-period delivery was associated with increased GDM independent of gestational weight gain, potentially related to stress-mediated metabolic dysregulation, dietary quality changes, or reduced physical activity beyond caloric excess. First-trimester lockdown exposure showed the strongest association with GDM risk. These findings underscore the need for proactive interventions during public health emergencies, including digital health infrastructure, early pregnancy support, and integrated mental health care.