Effects of Diabetes on the Baby

Having diabetes automatically makes a pregnancy high risk because of the many potentially negative effects on the baby as well as the mother. However, the chances of a baby being born with diabetes are extremely rare, particularly in cases where the mother has gestational diabetes.

If the pregnant mother does not have good control over her blood sugar, excess amounts of blood sugar (the baby's food source) are transported to the baby through the placenta. Since the baby does not have diabetes, he/she is able to increase the production of insulin substantially in order to use this extra sugar, but this cycle can result in several complications.

Possible Complications

Macrosomia (large baby)

Macrosomia refers to a baby born weighing more than 4,000g (8.8 pounds) or born at greater than the 90th percentile for the gestational age. The large amounts of insulin produced as a result of the mother's high blood sugar gets converted into body fat, so that the baby is "overfed" while inside the uterus.

This makes delivery harder for both the baby and the mother, with an increased risk of injury to both. A baby being too large also increases the chances of a cesarean delivery being necessary.

Most obstetricians perform an ultrasound to estimate the fetal weight before delivery to determine if it's safe to attempt a vaginal delivery. Trying to deliver a very large baby vaginally, particularly when the mother has diabetes, can result in one of the most frightening obstetrical emergencies, a shoulder dystocia, where the baby's head delivers but the shoulders are too large to fit through the birth canal.

Neonatal hypoglycemia

Neonatal hypoglycemia refers to a baby having too low blood sugars after birth. If the baby's pancreas is making large amounts of insulin in response to the mother's high blood sugars, it will continue to do so for a time after delivery; however, after delivery, the mother is no longer providing glucose, which can cause the baby's blood sugar to drop too low. This can lead to fussiness, jitteriness and a chance the baby will have trouble breathing or might have a seizure.

Because of these potential complications, most babies born to women with diabetes are closely monitored or the first few hours of life, including frequent heel sticks to check their blood sugars. These babies may require more frequent breast or bottle-feeding to maintain their blood sugars at a normal range. In some cases they need intravenous fluids with glucose.

Other neonatal metabolic problems

In addition to hypoglycemia, excess insulin can also (but not often) cause other metabolic complications such as jaundice (yellowing of the skin) and imbalances of calcium or magnesium. 

Type 2 diabetes tends to run in families, so offspring may be at increased risk for developing it in adulthood. Children of mothers with Type 1 diabetes have less than a 5% chance of developing diabetes during childhood. In fact, the baby has a greater risk if his/her father, not the mother, has Type 1 diabetes.

Stillbirth

Chronically high blood sugars can result in blood vessel damage in the placenta and poor oxygen and nutrient supply to the baby. This decrease in oxygen may cause health damage as serious as death or stillbirth. This rarely occurs in pregnancies complicated by gestational diabetes, and is more likely to occur if the mother had diabetes (either Type 1 or 2) before the pregnancy (pre-gestational diabetes). Because of this, women with pre-gestational diabetes should be monitored more closely toward the end of pregnancy.

Birth defects

In the general population, there is about a 2 to 3% risk of having a baby with a major birth defect. Babies born to mothers with gestational diabetes do not have a greater risk of birth defects than the general population.

In women with pregestational diabetes, however, this risk increases about three to fourfold, particularly if blood sugars are high during the early weeks of pregnancy when the baby's vital organs are developing. The risk for having a baby with one of these birth defects is directly correlated with how poorly the blood sugar was controlled during the first few weeks of pregnancy.

The most common birth defects are those of the brain, spinal cord and heart. The majority can be detected during the first half of the pregnancy with ultrasound studies and prenatal diagnostic tests.

Having diabetes does not increase the risk for having a baby with a chromosome problem such as Down syndrome over the age-related risk. The key to minimizing the risks for having a baby with a birth defect is to seek preconception medical care in order to optimize blood sugar control before becoming pregnant.