Much of the existing literature has focused on low maternal Hb during pregnancy; however, our review demonstrates that high maternal Hb concentrations during this time are likewise associated with up to a 2-fold increased odds of adverse infant outcomes (VLBW, PTB, SGA and stillbirth) and maternal outcomes (pre-eclampsia, gestational diabetes and maternal mortality). The gene discussed is GSTM1; the disease is Stillbirth.