Differential associations between body composition indices and neurodevelopment during early life in term-born infants: findings from the Pakistan cohort: Multi-Center Body Composition Reference Study

Objective: To examine associations between fat free mass (FFM) and fat mass (FM) accretion during the first 1000 days of life and neurodevelopment in term-born, low-risk infants from Karachi, Pakistan. Design: Prospective, observational study nested within the Multi-Center Body Composition Reference Study. FFM, FM, and fat% were estimated using the deuterium dilution method; neurodevelopmental outcomes were assessed at 24 months using the INTER-NDA (n = 132). Results: Children with gross motor delays had significantly lower FFM at 18 months (8.01 ± 0.97 kg vs. 7.55 ± 0.20 kg). Children with positive and negative behavior problems had significantly higher fat% at 24 months (20.62 ± 4.30% vs. 18.23 ± 5.46% and 20.89 ± 4.24% vs. 18.54 ± 5.38%). No associations remained significant after adjusting for covariates. Trajectory modeling showed that between 12 and 18 months, negative behavior scores changed by 13.8 points for every SD change in fat accretion. Conclusions: Findings highlight the importance of balancing neurodevelopment and metabolic risk when designing nutritional interventions for young children.