The Network for the Advancement of Patient Blood Management, Haemostasis, and Thrombosis recommends consideration of IV iron in pregnant women who fail to respond to oral iron supplementation within 2 to 4 weeks of initiation of therapy, those with severe anemia (Hb < 8.0 g/dL), or newly diagnosed IDA beyond 34 weeks of gestation.[32] In general, IV iron formulations resulted in adverse effects such as hot flushes, chest tightness, headache, nausea, vomiting, mild fever, arthralgia, and anaphylaxis caused by the toxic reaction of free iron. This evidence concerns the gene GSTM1 and anaphylaxis.