According to the American Diabetic Association, there are 135,000 cases of gestational diabetes per year. In diabetes, the body does not make enough insulin to properly metabolize glucose. The extra glucose that the mother produces crosses the placenta and causes the baby to make excess insulin. Hyperglycemia or high blood sugar causes complications in the unborn baby.
Macrosomia
Macrosomia is defined as a birth weight of greater than 4500 grams by the American College of Gynecologists and Obstetricians. This is approximately a 9.9 pound baby. Because of the excess glucose the baby receives and the increased insulin the baby makes, the extra glucose is stored as fat in the baby. Macrosomia puts the infant and mother at risk. The infant can suffer a collar bone injury or a skull fracture in the birth canal. Mothers with macrosomic infants are more likely to have cesarean births.
Shoulder Dystocia
Shoulder dystocia occurs when the baby's shoulder cannot pass the mother's pubic bone during delivery, and gets trapped in the birth canal. This is an obstetrical emergency because the baby could die in the birth canal. Shoulder dystocia typically occurs in large infants, such as those with macrosomia. Postpartum hemorrhage and large episiotomies can also occur because of shoulder dystocia. Special maneuvers are required for delivery of the baby, which may result in a brachial plexus injury. The brachial plexus is a ball of nerves under the arm that controls movement in the arm. Four to 15 percent of infants with shoulder dystocia will suffer brachial plexus palsies.Most resolve on their own, but approximately 10 percent of the injuries have permanent effects.
Other Complications
Hyperglycemia in the mother is associated with other complications in the baby. Poorly controlled diabetes in early pregnancy can cause miscarriages and birth defects. Spina bifida, a defect of the spinal cord; anencephaly, being born without a brain; openings in the lip or roof of the mouth; and limb deficiencies are all associated with maternal hyperglycemia. Infants can be born with polycythemia which is an increase in the number of red blood cells. This increases the thickness of the blood and can result in decreased oxygen delivery to vital organs, which can result in death. Hyperglycemia is also associated with premature delivery, pre-eclampsia during pregnancy, and the need for neonatal intensive care.
