COVID-19 Lockdowns and Gestational Diabetes Risk: Identifying Critical Windows for Prevention

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 conferred highest risk (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, suggesting stress-related metabolic dysregulation and dietary quality changes beyond caloric excess. First-trimester lockdown exposure represents a critical vulnerability window. These findings underscore the need for proactive interventions during public health emergencies, including digital health infrastructure, early pregnancy support, and integrated mental health care.