A glucose metabolism impairment occurs in about 2-3% of all pregnancies. Two different groups of women are involved: diabetic women who become pregnant and healthy women developing gestational diabetes or glucose intolerance during pregnancy. Due to therapeutic improvements and new techniques of fetal monitoring, maternal and perinatal mortality now approaches that of normal pregnancies. On the contrary, congenital anomalies are still four times more frequent. A good control of the mother metabolism is necessary to reduce complications in fetal development, especially during the first six weeks, a crucial period for the early cell division. Fetal monitoring is very important not only to control the normality of the growth and the well-being of the fetus, but also for early identification of possible anomalies.