IV Iron in pregnancy: An unmet clinical need
Authors: Michael Auerbach
Journal: American Journal of Hematology (2014)

To the editor: This is the second in a series of short commentaries on the clinical use of intravenous iron. The American Journal of Hematology welcomes comments and questions, which will be addressed in the subsequent issue. Approximately 58% of normal, nonanemic, menstruating college freshmen have no stainable iron in their marrow. A recent French survey 1 reported 25% of menstruating women were iron deficient 1. Given these staggering numbers, it is not surprising that iron deficiency with or without anemia is common in pregnancy yet unless anemia is present at the initial visit, iron parameters are not routinely ordered. While oral iron remains front line standard for gravidas in the western world, bloating and constipation are common problems due to the high progesterone levels, which slow bowel transit and increasing pressure of the gravid uterus on the rectum. Oral iron, rife to gastrointestinal perturbation, is associated with reported adverse events in up to 70% to whom it is prescribed, resulting in poor adherence 2. Whereas numerous publications report the safety and efficacy of intravenous iron in gravidas without reported serious adverse events when given in the second or third trimester, its use in pregnancy is sporadic at best. It is likely that this reluctance to use intravenous iron is fueled by antiquated data reporting serious adverse events, such as anaphylaxis, which were much more common with older preparations no longer available. The advent of new formulations allowing complete replacement doses in a single setting, with marginal to no toxicity in gravidas, should obviate such concerns. Unfortunately, that has not occurred. In 2011, a report published in this journal, demonstrated the safety and efficacy of 1,000 mg of low molecular weight (LMW) iron dextran administered in 1 hr to 888 patients receiving 1,266 infusions, 162 of whom were pregnant 3. Similar safety and efficacy data have been published with multiple doses of iron sucrose and total dose infusions of the newly approved agent ferric carboxymaltose. In all studies, rapid elimination of fatigue, pagophagia (ice craving), and less recognized symptoms, such as restless legs, was observed. No clinically significant toxicity has been reported. These observations are especially poignant considering that Congdon et al. reported that not only do iron deficient neonates have delayed growth and development but also a statistically significant increment in cognitive and behavioral abnormalities can be detected up to 10 years after iron repletion 4. In our practice, we routinely administer 1,000 mg of LMW iron dextran to iron deficient gravidas intolerant of or unresponsive to oral iron independent of anemia. Approximately 1,400 pregnant women have been treated since 1991 when LMW iron dextran was approved for use in iron deficient patients in the United States. No serious adverse events have been observed. Given the preponderance of published evidence on the safety and efficacy of intravenous iron in pregnancy, the failure to address its use is an unmet clinical need and a more liberal use of IV iron will minimize the likelihood that the neonate born to an iron deficient mother will be iron deficient at birth. These data also suggest that the current guidelines of the American College of Obstetrics and Gynecology, which do not recommend the routine screening for iron deficient at the initial prenatal visit, should be revisited. Michael Auerbach Clinical Professor of Medicine Georgetown University School of Medicine Auerbach Hematology and Oncology, Baltimore, Maryland