1. Introduction
’s behavior, SD
UNDERNUTRITION, UNDERNUTRITION
These authors contributed equally to this work.Undernutrition and a lack of learning opportunities can jeopardize long-term growth and development among infants in low- and middle-income countries. We conducted a 6-month 2 × 2 cluster-randomized trial to assess the effects of multiple micronutrient-fortified beverages and responsive caregiving interventions among infants 6–18 months in 72 community sectors in southwest Guatemala. We administered baseline and endline assessments of childhood development (Bayley Scales of Infant and Toddler Development) and socioemotional development (Brief Infant Toddler Socio-Emotional Assessment) and measured ferritin and hemoglobin on a subsample. The trial was analyzed using linear mixed models. At the baseline, the mean age (SD) was 13.0 (4.6) months, including 49% males, 32% who were stunted, 55% who were anemic, and 58% who were iron deficient. At the endline (Early childhood development lays the foundation for subsequent learning throughout the life course and is associated with health, schooling attainment, and earning potential, and with individual, family, and societal implications [Healthy brain development includes dendritic branching, synapse maturation and function, and myelination is dependent on adequate nutrition, including multiple micronutrients [Responsive caregiving refers to caregivers’ prompt, age-appropriate, and sensitive response to children’s behavior [Integrating nutrition and responsive caregiving interventions may be an efficient use of resources to promote early childhood development. Meta-analyses and systematic reviews of combined interventions have shown specificity, with beneficial effects on nutrition attributable to nutrition components and beneficial effects on development attributable to psychosocial components, with few investigations of synergistic effects [Guatemala provides a unique opportunity to investigate the impact of combined nutrition and responsive caregiving interventions. Guatemala has one of the highest rates of undernutrition seen globally, and the highest in Latin America. Over 45% of children < 5 years are stunted (height-for-age The objective of this study was to evaluate the independent and synergistic effects of multiple micronutrient supplementation and responsive caregiving interventions on young children’s development and nutritional status in rural Guatemala. The study was designed to test three hypotheses: (1) multiple micronutrient-fortified beverage groups will have better development and nutritional status compared to placebo groups, (2) responsive caregiving groups will have better development than groups without responsive caregiving, and (3) the combined multiple micronutrient-fortified beverage and responsive caregiving group will have better development than the other three groups, attributed to synergistic effects. 