Although diabetes alters hormonal profiles at the hypothalamic, pituitary and gonadal levels, yet the mechanism of diabetes-associated impaired expression of endometrial differentiation to deciduoma or pregnancy failure in rats is not well clarified. This book, therefore, presents studies to clarify the mechanism that leads to impaired endometrial decidualization in diabetic pseudopregnant rats or the fetoplacental changes including overall pregnancy outcome in the diabetic pregnant rats. The findings showed that diabetes-associated estrogen deficiency in pseudopregnant rats is possibly caused by ACTH-activated high levels of testosterone of adrenal origin. Diabetes-associated fetal growth retardation in the first or final half of pregnancy is primarily caused by progesterone deficiency. This book provides good reference for undergraduate and postgraduate students doing research in reproductive physiology.