Changes in iron status during pregnancy in Peruvian women receiving prenatal iron and folic acid supplements with or without zinc

Background: Iron deficiency anemia is the most prevalent nutrient deficiency during pregnancy, yet there are few data on the effect of prenatal iron supplementation in women in developing countries. Objective: Our objective was to describe the effect of iron supplementation on hematologic changes during pregnancy, and the effect on those changes of adding zinc to the supplements. Design: pregnant women were enrolled in a randomized, double-masked study conducted at a hospital in a shantytown in Lima, Peru. Women were supplemented daily from 10-24 wk gestation to 4 wk postpartum with 60 mg Fe and 250 mu g folic acid with or without 15 mg Zn. Hemoglobin and ferritin concentrations were measured in 645 and 613 women, respectively, at enrollment, at 28-30 and 37-38 wk; gestation, and in the cord blood of 545 neonates. Results: No differences in iron status were detected by supplement type, but hematologic changes were related to initial hemoglobin status. Women with anemia (hemoglobin <110 g/L) showed steady increases in hemoglobin concentration throughout pregnancy whereas women with relatively higher initial hemoglobin concentrations had declining values during mid pregnancy, then rising values by 37-38 wk gestation. Women with an initial hemoglobin concentration >95 g/L showed increases in serum ferritin by the end of the pregnancy. Despite supplementation, women with poorer hematologic status; who were younger, single, and multiparous; and who consumed fewer supplements were more likely to have anemia at the end of pregnancy. Conclusions: These hematologic changes are congruent with the effects of iron supplementation reported in placebo-controlled trials and the addition of zinc did not significantly affect them.