Why are iron requirements lower for breastfeeding mothers compared with pregnant women?

Breastfeeding mothers have increased iron absorption from the gut due to prolactin-mediated upregulation of enterocyte iron transporters, raising requirements to levels higher than during pregnancy.

Iron requirements decrease because breast milk is loaded with maternal ferritin and transferrin that fully compensate for maternal iron needs and allow menstrual cycles to continue with increased iron recycling.

Breast milk contains relatively little iron and lactational amenorrhea commonly suppresses menstrual blood loss, so maternal iron losses are reduced and dietary needs fall to about 9 mg/day.

Breastfeeding mothers lose significant iron through milk, so the RDA is increased rather than decreased; the decrease in recommended intake is primarily a historical artifact with no physiological basis.