There are two types of diabetes that occur in pregnancy:
Gestational diabetes--when a mother who does not have diabetes before becoming pregnant develops a resistance to insulin because of the hormones of pregnancy.
Pregestational diabetes--women who already have insulin-dependent diabetes and become pregnant.
With both types of diabetes, there can be complications for the baby. It is very important for a mother to maintain very close control of her diabetes during pregnancy.
The placenta supplies a growing fetus with nutrients and water, as well as produces a variety of hormones to maintain the pregnancy. Some of these hormones (estrogen, cortisol, and human placental lactogen) can have a blocking effect on insulin. This is called contra-insulin effect, which usually begins about 20 to 24 weeks into the pregnancy.
As the placenta grows, more of these hormones are produced, and insulin resistance becomes greater. Normally, the pancreas is able to make additional insulin to overcome insulin resistance, but when the production of insulin is not enough to overcome the effect of the placental hormones, gestational diabetes results.
Pregnancy also may change the insulin needs of a woman with existing diabetes as a medical condition. Insulin-dependent mothers may require more insulin as pregnancy progresses, sometimes as much as 30 percent over the prepregnancy dose.
About 5 percent of all pregnant women in the U.S. are diagnosed with gestational diabetes. Gestational diabetics make up the vast majority of pregnancies with diabetes. Some pregnant women require insulin to treat their diabetes.
The mother's excess amounts of blood glucose are transferred to the fetus during pregnancy. This causes the baby's body to secrete increased amounts of insulin, which results in increased tissue and fat deposits. The infant of a diabetic mother (IDM) is often larger than expected for the gestational age.
The infant of a diabetic mother may have higher risks for serious problems during pregnancy and at birth. Problems during pregnancy may include increased risk of birth defects and stillbirth. It is thought that poor control of blood glucose is linked to the development of congenital abnormalities. These may include abnormalities in the formation of the heart, brain, spinal cord, urinary tract, and gastrointestinal system.
Unlike insulin-dependent diabetes, gestational diabetes generally does not cause birth defects. Birth defects usually originate sometime during the first trimester (before the 13th week) of pregnancy. But, the insulin resistance from the contra-insulin hormones produced by the placenta does not usually occur until approximately the 24th week. Women with gestational diabetes generally have normal blood glucose levels during the critical first trimester.
A newborn infant of a diabetic mother may develop one, or more, of the following:
Hypoglycemia refers to low blood glucose in the baby immediately after delivery. This problem occurs if the mother's blood glucose levels have been consistently high, causing the fetus to have a high level of insulin in its circulation. After delivery, the baby continues to have a high insulin level, but it no longer has the high level of glucose from its mother, resulting in the newborn's blood glucose level becoming very low. The baby's blood glucose level is checked after birth, and if the level is too low, it may be necessary to give the baby glucose intravenously.
Macrosomia refers to a baby that is considerably larger than normal. All of the nutrients the fetus receives come directly from the mother's blood. If the maternal blood has too much glucose, the pancreas of the fetus senses the high glucose levels and produces more insulin in an attempt to use this glucose. The fetus converts the extra glucose to fat. Even when the mother has gestational diabetes, the fetus is able to produce all the insulin it needs. The combination of high blood glucose levels from the mother and high insulin levels in the fetus results in large deposits of fat which causes the fetus to grow excessively large.
Birth injury may occur due to the baby's large size and difficulty being born.
Respiratory distress (difficulty breathing)
Too much insulin in a baby's system due to diabetes can delay surfactant production which is needed for lung maturation.
Treatment of a baby born to a diabetic mother often depends upon the control of diabetes during the last part of pregnancy and during labor. Specific treatment will be determined by your baby's physician based on:
Your baby's gestational age, overall health, and medical history
Extent of the condition
Your baby's tolerance for specific medications, procedures, or therapies
Expectations for the course of the condition
Your opinion or preference
Treatment may include:
Careful monitoring of blood glucose levels
Blood may be drawn from a heel stick, with a needle in the baby's arm, or through an umbilical catheter (a tube placed in the baby's umbilical cord).
Giving the baby a quick source of glucose
This may be as simple as giving a glucose and water mixture as an early feeding. Or, the baby may need glucose given intravenously. The baby's blood glucose levels are closely monitored after treatment to watch for hypoglycemia to occur again.
Checking for hypocalcemia (low calcium levels) which may also occur in IDM
Giving oxygen or using a breathing machine (if respiratory distress occurs)
Care for any problems arising from a birth injury
Care for any problems that occur with a birth defect
Prenatal care is essential to a healthy outcome when a mother has diabetes in pregnancy. Careful diet management, blood glucose monitoring, and insulin therapy can help keep a mother's blood glucose levels at normal levels and decrease many of the risks to her baby.