GSTM1 and gestational diabetes: Interestingly, studies assessing maternal early pregnancy Hb levels and GDM risk have indicated that among the normal variation of Hb levels, lower Hb levels associate with a reduced risk of GDM and some other cardiometabolic dysfunctions without having detrimental effects on fetus or placenta (Abeysena et al., 2010; Sissala et al., 2022).