Long-Term Effects of Multiple-Micronutrient Supplementation During Pregnancy, Lactation, and Early Childhood on the Cognitive Development of Children Aged 4–14 Years: A Systematic Review of Randomized Controlled Trials

<b>Background:</b> Inadequate nutrition, poor health care, and limited stimulation constrain early childhood development and cognitive potential. Micronutrient deficiencies during pregnancy and early life are prevalent in low- and middle-income countries (LMICs) and may impair cognitive outcomes. Maternal multiple-micronutrient (MMN) and point-of-use micronutrient powder (MNP) supplements improve birth outcomes and iron status, but their long-term cognitive impact remains unclear. This systematic review assessed the long-term impact of maternal MMN and early-childhood MNP supplementation on cognitive development among children aged 4-14 years in LMICs. <b>Method:</b> Following PRISMA guidelines (PROSPERO CRD42023459846), (cluster) randomized controlled trials were identified from six databases and gray literature (October 2023; updated July 2025). Records were managed in EndNote and screened in Covidence, and data were synthesized using Review Manager. Eligible studies examined MMN or MNP interventions during pregnancy, lactation, or early childhood, reporting cognitive, motor, or socio-emotional outcomes in children aged 4-14. <b>Results:</b> Ten studies met the inclusion criteria: six on maternal supplementation, three on early childhood interventions, and one combining both. Most were conducted in Asia, with one in Tanzania and one in Peru. Although most findings were not statistically significant, two large UNIMMAP-based trials indicated modest long-term improvements in procedural memory and intelligence, while one early childhood point-of-use MNP trial suggested enhanced pre-academic skills. <b>Conclusions:</b> Maternal MMN supplementation may modestly enhance specific domains of cognitive development, whereas evidence on the long-term effects of MMN and point-of-use MNPs on cognitive development remain limited, highlighting the necessity for further research.