Both iron deficiency and iron excess during the fetal and neonatal period bode poorly for developing organ systems. Maternal conditions such as iron deficiency, diabetes mellitus, hypertension and smoking, and preterm birth are the common causes of perinatal iron deficiency. Long-term neurodevelopmental impairments and predisposition to future iron deficiency that are prevalent in infants with perinatal iron deficiency require early diagnosis, optimal treatment and adequate follow-up of infants at risk for the condition. However, due to the potential for oxidant-mediated tissue injury, iron overload should be avoided in the perinatal period, especially in preterm infants.