Effect of Health Belief Model-Based Nutrition Education Intervention on Nutritional Status of Pregnant Women in Rural Western Ethiopia: A Cluster Randomized Controlled Trial, 2026

Maternal undernutrition affects 19.5% to 41.2% of pregnant women in Ethiopia, with limited progress from conventional programs.Despite the recognized benefits of theory-driven approaches, behavioral frameworks to guide maternal nutrition education interventions are not explored through interventional designs in severely affected rural pastoralist settings.This community-based, two-arm cluster-randomized controlled trial evaluated the effectiveness of a Health Belief Model-based nutrition education intervention in promoting nutritional status among 328 pregnant women (164 per arm) in rural Nuer Zone, Gambella Region, Western Ethiopia, from March to June 2026.A standard non-stretchable Middle-Upper Arm Circumference (MUAC) tape was used to assess nutritional status.Linear Mixed-Effects Models with Mediation analysis were employed to test intervention effects and pathways through Health Belief Model (HBM) constructs.At baseline, the prevalence of undernutrition (MUAC < 23 cm) was comparable between intervention and control groups (30.2% vs. 24.5%,respectively, p = 0.285), and mean MUAC values were similar (24.08 cm vs. 24.28cm, p = 0.285).At endline, the intervention group showed a 1.334 cm increase in mean MUAC, compared with a 0.455 cm decline in controls (DiD = 1.789 cm, 95% CI: 1.485-2.093,p < 0.001).Likewise, undernutrition prevalence decreased from 30.2% to 5.6% in the intervention group, while it increased from 24.5% to 26.4% in controls, with changes in HBM constructs mediating 51.4% of the intervention effect.The HBM-based education intervention significantly improved nutritional status among pregnant women in rural western Ethiopia.Integrating theory-driven behaviour change approaches into Ethiopian maternal nutrition programs is recommended.