Iron deficiency and Plasmodium falciparum infection during pregnancy.

To the Editor—Iron deficiency during pregnancy is particularly common in sub-Saharan Africa, where Plasmodium falcip-arum infection is another frequent cause of anemia. Because of the detrimental impact of anemia on the mother and the fetus, the World Health Organization universally recommends iron (and folate) supplementation, as well as malaria-prevention treatment, during pregnancy [1]. Iron supplementation has long been suspected to increase susceptibility to malaria [2], and a recent trial in malaria-holoendemic Zanzibar suggested that routine supplementation with iron and folate in children can result in an increased risk of severe illness and death [3]. A recent article by Kabyemela et al. [4] in the Journal raises additional concern. They report that, in Tanzanian pregnant women, iron deficiency was associated with an 80% reduction in the risk of placental malaria. This finding gives rise to the conclusion that iron supplementation for pregnant women in tropical regions may carry unrecognized risks and should be validated in large-scale clinical trials. We reanalyzed data from a cross-sectional survey conducted in 1998 among 530 pregnant women in southern Ghana, an area of malaria holoendemicity [5]. Preceding the implementation of intermittent preventive treatment, almost 2 of 3 women attending antenatal care clinics in this area harbored P. falciparum, as evidenced by PCR analysis of peripheral blood samples, positive results of which almost invariably correspond to placental infection [6]. By use of the definition of iron deficiency (i.e., a ferritin level of Ͻ30 ng/mL, or Ͻ70 ng/mL if the C-reactive protein level was Ͼ8.2 ng/mL) and statistical analyses specified by Kabyemela et al. [4], we found that iron deficiency reduced the risk of P. falciparum infection in pregnant Ghanaian women by 33% (table 1). With regard to microscopically visible parasitemia only, the prevalence of infec