The Updated Dual Burden of Malnutrition Among Vietnamese School-Aged Children: A Nationwide Cross-Sectional Study

<b>Objective:</b> To assess the prevalence and associated factors of malnutrition-including stunting, thinness, overweight, and obesity-among Vietnamese children aged 6-17 years, and to identify demographic, geographic, and behavioral correlates to inform targeted nutrition interventions. <b>Methods:</b> A cross-sectional, nationally representative study was conducted from January 2024 to June 2025 using data from the MIDU Assessment Program. A multistage stratified random sampling approach recruited 43,505 children aged 6-17 years across all regions of Vietnam. Anthropometric measurements were obtained following WHO 2007 growth reference standards. Stunting was defined as height-for-age Z-score (HAZ) < -2 SD, and overweight/obesity as body mass index-for-age Z-score (BAZ) > +1 SD. Data on demographic characteristics, sleep patterns, sports participation, vitamin K₂ use, and pubertal status were collected via structured questionnaires. Multivariable logistic regression was used to identify factors associated with stunting and overweight/obesity. <b>Results:</b> Overall, 3.9% were stunted, 5.1% were thin, 20.7% were overweight, and 11.4% were obese; 8.6% had any undernutrition and 39.5% had any form of malnutrition. Stunting was significantly associated with being male (OR = 1.37, 95% CI: 1.24-1.52), older age-particularly 14-17 years (OR = 6.56, 95% CI: 5.48-7.84)-and residing in the Northern midlands, North Central, South Central, and Central Highlands regions. In contrast, frequent sports participation (OR = 0.76, 95% CI: 0.68-0.84), daily vitamin K₂-MK₇ use (OR = 0.82, 95% CI: 0.72-0.93), and having reached puberty (OR = 0.26, 95% CI: 0.22-0.30) were associated with lower odds of stunting. For overweight and obesity, lower odds were found among females (OR = 0.48, 95% CI: 0.46-0.51) and older children, while higher odds occurred among those living in the Southeast (OR = 1.45, 95% CI: 1.36-1.53) and Mekong River Delta (OR = 1.35, 95% CI: 1.24-1.48) regions. Early sleep (OR = 0.91, 95% CI: 0.87-0.95) and sports participation (OR = 1.07, 95% CI: 1.02-1.11) showed modest associations, whereas vitamin K₂ use and puberty were not significant predictors. <b>Conclusions:</b> Vietnamese school-aged children face a significant rate of malnutrition, with regional, gender, and age disparities.