The World Health Organization (WHO) defines anemia during pregnancy as hemoglobin (Hb) <11 g/dL at any time during pregnancy, including mild (10–10.9 g/dL), moderate (7.0 and 9.9 g/dL), and severe anemia (<7.0 g/dL) [1]. The gene discussed is GSTM1; the disease is anemia (phenotype).