All expectant mothers look forward to the birth of a healthy newborn and prenatal care is an important step toward that goal, especially to monitor fetal growth when a baby seems too small or too large. Regular examinations during pregnancy that show a large baby can also help identify a mother who may have undetected diabetes, which is the most common cause of larger than average babies. Diabetes during pregnancy causes the mother’s increased blood sugar (glucose) to circulate to the baby, and in response the baby’s body makes insulin.