Elucidating the Determinants of Child and Maternal Malnutrition in Select South Asian Countries: A Multinomial Logistic Approach

South Asia faces a difficult nutrition transition, where chronic undernutrition persists alongside increasing overweight and obesity. We develop a mother-child dyad-level classification framework to capture malnutrition burdens and their correlates. Using nationally representative DHS data from Bangladesh, India, Maldives, Nepal, and Pakistan, mother-child pairs are classified into single-member malnutrition (HSBM), single burden of malnutrition (SBM), and double burden of malnutrition (DBM). Country-specific multinomial logit models show mother--daughter pairs face significantly lower odds of SBM and DBM than mother-son pairs in India (SBM: RRR = 0.882***; DBM: RRR = 0.884***), with more strongly in Maldives (SBM: RRR = 0.469***; DBM: RRR = 0.724**). Pakistan shows the reverse, with mother-son pairs at lower SBM risk (RRR = 1.636***). Third-or-later-born children face higher DBM risk across countries. Well-nourished dyads decline steadily with age while DBM rises. Wealth's effect is mixed: the richest quintile protects against SBM everywhere but raises DBM risk in India and Pakistan.