Iron deficiency anemia (IDA) is that the synthesis of Hb and iron-containing enzymes is reduced due to lack of iron, for which the main causes during pregnancy are insufficient iron content in the diet [7], iron absorption disorder (e.g., iron absorption disability and dietary iron predation of gut microbiome) [7], increased iron requirement/uptake of the placenta and fetus [7,8], and increased need to fuel red blood cell mass [9]. The gene discussed is GSTM1; the disease is anemia.