Iron deficiency is a global health issue among preschool children that is associated with impaired neurodevelopment affecting cognitive, motor, and behavioural abilities. High growth velocity combined with limited ability to absorb iron results in markedly reduced iron stores during the first year of life.3 Iron deficiency affects 5% to 25% of preschool children in high-income countries and up to 100% of young children in low-income countries. Iron administration to high-risk groups is associated with improved psychomotor and cognitive development and fewer behavioural symptoms. Delaying umbilical cord clamping (CC) by 2 to 3 minutes after delivery allows foetal blood remaining in the placental circulation to be transfused to the newborn. This transfusion can expand the blood volume by 30% to 40% (25-30 mL/kg). After physiologic haemolysis, haemoglobin-bound iron is transferred into iron stores. Consequently, delayed CC is associated with improved iron status at 4 to 6months of age. Delayed CC has the potential to contribute approximately 75mg of iron, corresponding to more than 3months’ requirement in a 6- to 11-month-old infant. We have previously demonstrated a 90% reduction in iron deficiency at 4 months in healthy full-term infants who received delayed CC with no adverse neonatal effects. However, there is a lack of knowledge regarding the long-term effects and evidence of no harm, causing policymakers to be hesitant to make clear recommendations concerning delayed CC in full-term infants, especially in settings with rich resources. We hypothesized that delayed CC and the associated reduction of iron deficiency during the first 4 months of life would result in improved neurodevelopment. Therefore, we conducted a follow-up of a randomized clinical trial to assess the long-term effects of delayed CC compared with early CC on neurodevelopment at 4 years of age.