Despite its appropriateness, the Z-score methodology has been scarcely used in clinical trials of treatments for iron-deficiency anemia in pregnancy [19]; for instance, Mumtaz et al. (2000) were the only one to apply the Hb Z-scores among 23 clinical trials reviewed in the most recent meta-analysis [19,42]. The gene discussed is GSTM1; the disease is Iron deficiency anemia.