Single vs. Double Dose Iron Supplementation for Prevention of Iron Deficiency Anemia in Twin Pregnancy: A Randomized Controlled Clinical Trial

Introduction: It is estimated that about 18% of pregnant women suffer from iron deficiency anemia throughout their whole pregnancy. In twin pregnancy, owing to the relatively greater feto-placental requirements and greater expansion in maternal plasma volume and red cell mass, iron requirements are magnified 1.8 times compared to singleton pregnancies. However, for prevention of iron deficiency in twin pregnancy, only sparse data exist regarding the sufficiency of the standard antenatal iron supplementation dose used in singleton pregnancies to meet the increased iron demand. In this study, we investigate the effect of single and double dose iron supplementation for prevention of iron deficiency anemia in twin pregnancy. Methods: A randomized controlled clinical trial was conducted at our center in the period between February 2019 and October 2020, and included 450 eligible healthy non-anemic women aged 18 - 35 years, with twin pregnancy at 12 - 16 weeks of gestation. After informed consent, eligible women were randomized to receive either single dose 27 mg, or double dose 54 mg elemental iron supplementation. Monitoring of hemoglobin concentration was done at fixed time points during gestation: at enrollment, 24 weeks, 32 weeks and before delivery. The primary outcome of the study was the incidence of iron deficiency anemia during follow up until delivery. Results: The incidence of iron deficiency anemia in the two groups did not differ significantly between the single dose group (19.1%) and the double dose group (24.0%). In women who did not develop Iron Deficiency Anemia, hemoglobin concentration varied significantly along the different gestational ages during the follow up period. In contrast, they did not show an overall statistically significant difference in the hemoglobin concentrations between the single or double dose groups. Conclusion: This clinical trial did not demonstrate an added benefit for doubling prophylactic iron supplementation dose in non-anemic women with twin pregnancy.