Comparison of Oral Ferrous Sulfate to Intravenous Ferumoxytol in Antepartum Iron Deficiency Anemia

Evaluate the extent to which treatment of iron deficiency anemia beyond 24-34 weeks' gestation of pregnancy with intravenous iron increases hemoglobin compared to oral iron. The investigators will test the hypothesis that pregnant women who are anemic in the second and third trimester are more likely to significantly increase their hemoglobin with intravenous iron as opposed to the usual standard of care, oral iron.