Iron status and iron balance during pregnancy. A critical reappraisal of iron supplementation

Background. Iron supplementation in pregnancy is a controversial issue. The aim of this review was to summarize the results of relevant papers on this subject. Methods. Placebo-controlled studies on iron treatment in pregnancy were ide ntified from the Cochrane database. Results. Among fertile women, 20% have iron reserves of >500 mg, which is t he required minimum during pregnancy; 40% have iron stores of 100-500 mg, a nd 40% have virtually no iron stores. The demand for absorbed iron increase s from 0.8 mg/day in early pregnancy to 7.5 mg/day in late pregnancy. Dieta ry iron intake in fertile women is median 9 mg/day, i.e. the majority of wo men have an intake below the estimated allowance of 12-18 mg/day. Iron abso rption increases in pregnancy, but not enough to prevent iron deficiency an emia in 20% of women not taking supplementary iron. Iron-treated pregnant w omen have greater iron reserves, higher hemoglobin levels, and a lower prev alence of iron deficiency anemia than placebo-treated women both in pregnan cy as well as postpartum. Furthermore, children born to iron-treated mother s have higher serum ferritin levels than those born to placebo-treated moth ers. An iron supplement of 65 mg/day from 20 weeks of gestation is adequate to prevent iron deficiency anemia. Conclusions. In order to avoid iron deficiency in pregnancy, prophylactic i ron supplement should be considered. Iron supplements may be administered o n a general or selective basis. The selective approach implies screening wi th serum ferritin in early pregnancy, in order to identify women who can ma nage without prophylactic iron.