While it was beyond the scope of the current review, the association between postpartum maternal Hb and maternal and child health outcomes may also merit further examination, including a possible relationship between maternal anemia during lactation and breastmilk macronutrient composition.133 Furthermore, the majority of the literature that examines the role of the timing on health outcomes has focused on low Hb. Here, GSTM1 is linked to anemia (phenotype).