Infancy is the most rapid period of growth and development in human life. During the first 1000 days, from conception to a child’s second birthday, adequate nutrition shapes brain development, immune function, physical growth and long-term health outcomes. While advances in healthcare have reduced infant mortality worldwide, nutritional risk remains a significant public health challenge across both low- and high income countries. Malnutrition in infancy encompasses both undernutrition and overnutrition, each carrying immediate and lifelong consequences. Early recognition of nutritional risk factors and timely intervention are essential components of paediatric healthcare.