Effects of Diabetes on the Baby

Diabetes Effects on the Baby

Diabetes makes a pregnancy high risk. This is because diabetes can cause many potentially negative effects on the baby as well as the mother. Blood sugar is the baby's food source and it passes from the mother through the placenta to the baby.

When a woman has diabetes and her blood sugars are poorly controlled (too high), excess amounts of sugar are transported to the baby. 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. This abnormal cycle of events can result in several complications including:

Macrosomia (large baby)

Macrosomia refers to a baby born weighing more than 4,000g (8.8 pounds) or born at greater than the 90 percentile for the gestational age. In response to the excess amounts of sugar that the baby receives, large amounts of insulin are produced by the baby in order to convert the sugar into body fat. That is, the baby is being "overfed" while inside the uterus.

As a result, the delivery can be more difficult for the baby and the mother with increased risk for injury to both. In addition, the odds of requiring a cesarean delivery can be much greater when the baby is too large. Most obstetricians perform an ultrasound to estimate the fetal weight before delivery and to determine if it is 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 is defined as low blood sugars in the baby 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. Since the sugar supply from the mother is no longer present once the baby has delivered, blood sugar can drop too low (hypoglycemia, blood sugar < 40 mg/dl). The baby can become fussy, jittery or may even have a seizure or breathing problems.

Because of these possible complications, most babies born to women with diabetes will be monitored very closely for the first few hours of life with 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 and in some cases will require intravenous fluids with glucose.

Other Neonatal Metabolic Problems

In addition to hypoglycemia, the excess insulin can also infrequently be responsible for other metabolic complications such as jaundice (yellowing of the skin) and imbalances of calcium or magnesium. The chances of a baby being born with diabetes are extremely rare particularly in cases where the mother has gestational diabetes.

Type 2 diabetes tends to run in families and 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 has Type 1 diabetes.


When blood sugars are persistently high, blood vessel damage in the placenta and poor oxygen and nutrient supply to the baby can occur. This decrease in oxygen may cause health damage to the baby including 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 for 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, this risk is increased about three to fourfold particularly if blood sugars are high during the early weeks of pregnancy. This is the developmental time period when the baby is forming its vital organs. 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 of these birth defects 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.