For pregnant women, the trimester-wise classification proposed by the Center for Disease Control and Prevention (CDC) suggests that gestational anemia can be indicated by an Hb level of <6.83 mmol/L (<11 g/dL) in the first and third trimesters and that of <6.52 mmol/L (<10.5 g/dL) in the second trimester [4]. This evidence concerns the gene GSTM1 and anemia (phenotype).