Iron prophylaxis in pregnancy—general or individual and in which dose?

Abstract

Iron is mandatory for normal fetal development, including the brain. Iron deficiency may have deleterious effects for intelligence and behavioral development. It is important to prevent iron deficiency in the fetus by preventing iron deficiency in the pregnant woman. Iron deficiency anemia during pregnancy is a risk factor for preterm delivery and low birth weight. In the Western countries there is no consensus on iron prophylaxis to pregnant women. An adequate iron balance during pregnancy implies body iron reserves of ≥500 mg at conception. The physiologic iron requirements in the second half of gestation cannot be fulfilled solely through dietary iron. Iron supplements during gestation consistently increase serum ferritin and hemoglobin and reduce the prevalence of iron deficiency anemia. Iron has a negative influence on absorption of other divalent metals and increases oxidative stress in pregnancy, for which reason minimum effective iron dose should be advised. From a physiologic point of view, individual iron prophylaxis according to serum ferritin concentration should be preferred to general prophylaxis. Suggested guidelines are (1) ferritin >70 μg/l: no iron supplements; (2) ferritin 30–70 μg/l: 40 mg ferrous iron daily; and (3) ferritin <30 μg/l: 80–100 mg ferrous iron daily. In controlled studies, there are no documented side effects of iron supplements below 100 mg/day. Iron supplements should be taken at bedtime or between meals to ensure optimum absorption.