GSTM1 and anemia: However, in women with initial Hb < 10 g/dL, supplementation may be necessary to achieve Hb ≥ 12 levels, whereas in women with Hb ≥ 10, the process of blood hemoconcentration, the increase in iron reserve from erythrocyte mass, and postpartum iron savings, amenorrhea compensates for the small iron loss due to breastfeeding, and it may be sufficient for preventing anemia at six weeks [23,26].