It was observed that GDM placentas are characterized by increased antioxidant gene expression [Catalase (CAT) and glutathione reductase (GSR), but there was no difference in glutathione peroxidase and superoxide dismutase], and are less responsive to exogenous oxidative stress [hypoxanthine (HX)/xanthine oxidase (XO) treatment to release cytokines] than tissues obtained from normal pregnant women [7]. This evidence concerns the gene CAT and gestational diabetes.