This WHO guideline reviews the evidence on the safety and effectiveness of iron supplementation in postpartum women. The guideline suggests that 1) postpartum supplementation should begin as early as possible after delivery, and the iron-supplementation regimen should follow that used during pregnancy, or alternatively should follow that planned for menstruating women; and 2) in cases in which a woman is diagnosed with anemia in a clinical setting, she should be treated in accordance with the country’s policy, or with the WHO recommendation of daily iron supplements (120 mg of elemental iron plus 400 μg folic acid), until her hemoglobin concentration rises to normal.