Childhood Stunting in High-Burden Indian States: Socio-economic Determinants and POSHAN Abhiyaan Exposure

India records the largest absolute number of stunted children worldwide, yet evidence jointly examining socioeconomic determinants and national nutrition programme exposure in the highest-burden states remains limited. Objective: To identify socioeconomic determinants of stunting and to assess whether residence in districts with high POSHAN Abhiyaan implementation intensity is associated with lower odds of stunting among children under five. This cross-sectional study analysed secondary data from the National Family Health Survey (NFHS-5, 2019-2021) for 92,431 children aged 0-59 months in Bihar, Uttar Pradesh, Jharkhand, Madhya Pradesh, and Meghalaya. Stunting was defined as a height-for-age z-score below -2 SD of the WHO Child Growth Standards. Chi-square tests and multivariable binary logistic regression estimated adjusted odds ratios (AOR) with 95% confidence intervals (CI) using survey weights. Stunting prevalence was 41.6%. Low birth weight (AOR = 1.92; 95% CI 1.77-2.08), poorest wealth quintile (1.71; 1.58-1.85), short maternal height (1.63; 1.50-1.77), no maternal schooling (1.46; 1.34-1.59), inadequate dietary diversity (1.34; 1.24-1.45), and unimproved sanitation (1.28; 1.19-1.38) independently increased the odds of stunting, whereas high POSHAN Abhiyaan exposure was protective (0.86; 0.80-0.93). Stunting reflects converging household poverty, low maternal human capital, and intergenerational biological disadvantage; strengthening frontline nutrition services in low-coverage districts is essential.