Ten articles were identified for the relation between Hb level and Apgar score.12,19,20,25,26,28,29,31,33,34 Three of these studies concluded that maternal anemia is a risk factor for low 1- and/or 5-minute Apgar score, or leads to a lower mean 5-minute Apgar score compared with the group with normal maternal Hb.19,25,29 In contrast, 5 studies did not find any differences in Apgar score between anemic and nonanemic mothers.12,20,26,33,34 These contradictory findings are probably due to major differences in study design (retrospective and prospective cohort studies, and case-control studies). Here, GSTM1 is linked to anemia (phenotype).