Fetal bradycardia and acidosis during maternal parenteral iron: Case reports and literature review.

Iron deficiency anemia is an important problem among pregnant women, and intravenous (IV) iron infusions have been increasingly used. Whether fetal monitoring is required during infusion has been debated, with a recent guideline by Hematologists recommending against such. We report two cases of fetal bradycardia after iron isomaltoside (IIM), in women with otherwise good maternal and fetal health. Both developed dyspnea with desaturation minutes from infusion, followed by persistent fetal bradycardia. Both underwent category 1 CS, with cord arterial pH of 7.08 and 6.94 respectively. Upon literature review, only three case reports on fetal bradycardia in IV iron were identified. For older IV iron formulations, a case was reported after IV dextran test dose, while two cases after ferric gluconate were reported. For the new formulation IIM, only one case was reported so far, but in a woman with Crohn's disease and intrauterine growth restriction. IV iron in pregnancy carries risk of anaphylactic or hypersensitivity reactions, even with the newest formulations and in women with good maternal and fetal health. While rarely reported so far, fetal bradycardia is a possible consequence, commonly preceded by respiratory symptoms. Fetal monitoring should therefore be considered during infusion.