Gestational diabetes is the situation wherein pregnant woman faces hyperglycaemia for the first time in her life. During pregnancy, female body produce special hormones which may induce several metabolic changes in the body including insulin resistance in cells. Thus insulin, a blood glucose regulating hormone, though produced in sufficient levels, cannot be utilized efficiently by the body cells in some women. On the other hand, in some cases, the pancreas is unable to produce enough quantities of insulin. In both the situations, the blood will have high levels of circulating glucose. The foetus, developing inside the womb of a mother, will also eventually encounter these high levels of glucose and may result in complications such as increased fetal weight, prenatal, perinatal mortality and morbidity etc. Diabetic pregnancies often result in offsprings with several congenital structural and functional anomalies of the central nervous system, cardiac system, renal and gastrointestinal complications in human beings. Embryonic development is a tightly regulated biological process in which a number of growth and differentiation factors play crucial roles. Early embryos, wherein cell specification, morphogenesis and organogenesis are going on, are highly susceptible to physiological changes that may interfere with the embryonic development. One of the mechanisms by which glucose may induce embryonic malformations is thought to be by increasing oxidative stress. Antioxidants are the class of molecules which aid in handling oxidative stress induced by the excess amounts of reactive oxygen species. This book presents a systematic study wherein the effects of glucose on developing vertebrate embryos have been evaluated. The author further illustrates the role of antioxidants in alleviating the ill effects of glucose on developing embryos. Usually, gestational diabetes is asymptomatic and thus difficult to notice.