Iron deficiency (ID), defined as serum ferritin (SF) < 15 μg/L according to the WHO, is the most common nutritional deficiency worldwide and disproportionately affects pregnant women, being the main cause of anemia (generally defined as a hemoglobin (Hb) value < 110 g/L) in pregnancy [1]. The gene discussed is GSTM1; the disease is anemia.