Anemia in the 1st and 3rd trimester of pregnancy was defined by the Centers for Disease Control and Prevention in 1989 as hemoglobin (Hb) or hemotocrit less than 11 g/dL or 33%, respectively, and when the level of Hb or hemotocrit is less than 10.5 g/dL or 32%, respectively, in the 2nd trimester of pregnancy(1). This evidence concerns the gene GSTM1 and anemia (phenotype).