Gestational diabetes complicates 3% to 5% of all pregnancies. Shoulder dystocia and fetal injuries are associated with macrosomia, a complication often encountered in diabetic pregnancies. The route of delivery is often planned in advance and based on estimated fetal weight. Fetuses of diabetic mothers are prone to macrosomia due to increased subcutaneous adipose tissue deposits, and perinatal complications are more frequent in these fetuses. For this reason, particular effort should be directed toward the diagnosis of fetal growth abnormalities in fetuses of diabetic mothers. There are numerous formulas for estimating fetal weight, and they are all error prone. An effort should be made to follow these high-risk pregnancies in a longitudinal fashion to detect any developing growth abnormality as early as possible. Whether macrosomia or intrauterine growth restriction, early detection and careful planning of mode and time of delivery is the foundation of successful lowering of perinatal morbidity and mortality.