Materials and Methods: A total of 104 pregnant women at risk for gestational diabetes mellitus were enrolled in this triple-blind randomized controlled trial. The intervention protocol consisted of six 60-minute educational sessions focused on physical activity, which were theoretically grounded in the HBM. Participants in the control condition received only routine pregnancy care education. Data was conducted using SPSS version 21.

Results: The results showed that the levels of Perceived Susceptibility (28.63±3.79, P < 0.001), Perceived Threat Severity (28.48±1.79, p=0.015), Perceived Benefits (18.96±1.94, P = 0.022), and Self-Efficacy (17.85±3.40, P < 0.001) in the intervention group significantly increased after the education compared to before the education. In the intervention group, the amount of daily physical activity (18.07±3.66, P = 0.011) and weekly physical activity (74.26±26.99, P < 0.001) was significantly higher than before the intervention.

Conclusions: Sustaining and improving maternal health outcomes, particularly for pregnant individuals at elevated risk for gestational diabetes, mandates the adoption of structured educational models by policymakers and service providers, particularly practicing midwives. In this context, the implementation of the HBM is strongly recommended.