Intravenous Versus Oral Iron for Treating Iron-Deficiency Anemia in Pregnancy

Iron-deficiency anemia (IDA) is a common, undertreated problem in pregnancy. According to data from the U.S. National Health and Nutrition Examination Survey (NHANES), 25% of pregnant women in the U.S. have iron deficiency, with rates of 7%, 24%, and 39% in the first, second, and third trimesters, respectively. The prevalence of IDA is estimated at 16.2% overall and up to 30% at delivery. Iron deficiency is associated with significant adverse maternal and fetal outcomes including blood transfusion, cesarean delivery, depression, preterm birth, and low birth weight. Moreover, iron-deficient mothers are at risk of delivering iron-deficient neonates who, despite iron repletion, remain at risk for delayed growth and development. While treatment with iron supplementation is recommended during pregnancy, questions remain about the optimal route of delivery. Oral iron therapy, the current standard, is often suboptimal: up to 70% of patients experience significant gastrointestinal side effects (nausea, constipation, diarrhea, indigestion, and metallic taste) that prevent adherence to treatment, resulting in persistent anemia. Intravenous (IV) iron is an attractive alternative because it mitigates the adherence and absorption challenges of oral iron. However, IV iron costs more, and there are historical concerns about adverse reactions.

The American College of Obstetricians and Gynecologists (ACOG) recommends oral iron for the treatment of IDA in pregnancy, with IV iron reserved for the restricted group of patients. Our preliminary data show that this approach leads to 30% of patients with persistent IDA at delivery and an associated 3 to 6-fold increased risk of peripartum blood transfusion. ACOG's preferential recommendation of oral iron is based on paucity of data on the benefits and safety of IV iron, compared with oral iron, in pregnancy. Our published systematic review and meta-analysis showed that IV iron is associated with greater increase in maternal hemoglobin (Hb), but most of the primary trials were conducted in developing countries, included small sample sizes (50 - 252), and did not assess meaningful maternal and neonatal outcomes. The current Cochrane review noted that despite the high incidence and disease burden associated with IDA in pregnancy, there is paucity of quality trials assessing clinical maternal and neonatal effects of iron administration in women with anemia. The authors called for "large, good quality trials assessing clinical outcomes." The only large randomized trial of IV versus oral iron, conducted in India, showed no difference in a maternal composite outcome, but it is limited by use of iron sucrose which required five infusions, resulting in a wide range of iron doses (200 - 1600 mg). In addition, the primary composite outcome included some components not directly related to anemia. In contrast, our pilot trial of a single infusion of 1000 mg of IV low molecular weight iron dextran in pregnant women in the U.S. with moderate-to-severe IDA significantly reduced the rate of maternal anemia at delivery and showed promise for improving maternal morbidity by reducing rates of blood transfusion.

This is the first definitive double blind, placebo controlled, multicenter randomized trial in pregnant women in the U.S. (N=300) to test the central hypothesis that IV iron in pregnant women with IDA (Hb<11 g/dL and ferritin<30 ng/mL) at 13 - 30 weeks will be effective, safe and cost-effective in reducing severe maternal morbidity-as measured by maternal anemia at delivery-and will also improve offspring neurodevelopment. A multidisciplinary team of investigators in the U.S., will pursue the following specific aims:

Primary Aim: Evaluate the effectiveness and safety of IV iron, compared with oral iron, in reducing the rate of anemia at delivery in pregnant women with IDA.

Secondary Aim 1: Estimate the cost-effectiveness of IV iron , compared with oral iron, in pregnant women with IDA as measured by incremental cost per Quality Adjusted Life-year (QALY).

Secondary Aim 2: Assess the effect of IV iron, compared with oral iron, on offspring brain myelin content and neurodevelopment.