Almost 9 percent of women in the US have diabetes, but about one third of them do not know it. Women with diabetes have an increased risk of pregnancy complications.
In addition, 2 to 5 percent of women develop diabetes during pregnancy, called gestational diabetes.
Diabetes is a condition where sufficient amounts of insulin are either not produced or the body is unable to use the insulin that is produced. Insulin is the hormone that allows glucose to enter the cells of the body to provide fuel. When glucose cannot enter the cells, it builds up in the blood and the body's cells literally starve to death.
Diabetes in pregnancy can have serious consequences for the mother and the growing fetus. The severity of problems often depends on the degree of the mother's diabetic disease, especially if she has vascular (blood vessel) complications and poor blood glucose control. Diabetes that occurs in pregnancy is described as:
- Gestational diabetes - when a mother who does not have diabetes develops a resistance to insulin because of the hormones of pregnancy. Women with gestational diabetes may be non-insulin dependent or insulin dependent.
- Pre-existing diabetes - women who already have diabetes and become pregnant.
Gestational diabetes is a condition in which the glucose level is elevated and other diabetic symptoms appear during pregnancy in a woman who has not previously been diagnosed with diabetes. In most cases, all diabetic symptoms disappear following delivery. However, women with gestational diabetes have an increased risk of developing diabetes later in life, especially if they were overweight before the pregnancy.
Unlike other types of diabetes, gestational diabetes is not caused by a lack of insulin, but by blocking effects of other hormones on the insulin that is produced, a condition referred to as insulin resistance.
Although the cause of gestational diabetes is not known, there are some theories as to why the condition occurs.
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, 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.
Although any woman may develop gestational diabetes during pregnancy, some of the factors that may increase risk are:
- family history of diabetes
- having given birth previously to a very large infant, a stillbirth, or a child with a birth defect
- age (women who are older than 25 are at greater risk than younger women)
Although increased glucose in the urine is often included in the list of risk factors, it is not believed to be a reliable indicator for gestational diabetes.
A glucose screening test is usually performed between 24 and 28 weeks of pregnancy, which involves drinking a glucose drink followed by measurement of glucose levels after a one-hour interval.
If this test shows an increased blood sugar level, another test will be performed after a few days of following a special diet. The second test also involves drinking a glucose drink, and results are measured at three-hour intervals.
If results of the second test are in the abnormal range, gestational diabetes is diagnosed.
Specific treatment gestational diabetes will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment for gestational diabetes focuses on keeping blood glucose levels in the normal range. Treatment may include:
- special diet
- daily blood glucose monitoring
- insulin injections
Unlike other types of diabetes, gestational diabetes generally does not cause birth defects. Birth defects usually originate sometime during the first trimester of pregnancy. They are more likely in women with pre-existing diabetes, who may have changes in blood glucose during that time. Women with gestational diabetes generally have normal blood sugar levels during the critical first trimester.
The complications of gestational diabetes are usually manageable and preventable. The key to prevention is careful control of blood sugar levels just as soon as the diagnosis of gestational diabetes is made.
Infants of mothers with gestational diabetes are vulnerable to several chemical imbalances, such as low serum calcium and low serum magnesium levels, but, in general, the major problems of gestational diabetes include:
- 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.
- Hypoglycemia - refers to low blood sugar in the baby immediately after delivery. This problem occurs if the mother's blood sugar 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 sugar from its mother, resulting in the newborn's blood sugar level becoming very low. The baby's blood sugar level is checked after birth, and if the level is too low, it may be necessary to give the baby glucose intravenously.
- Respiratory distress (difficulty breathing) - too much insulin or too much glucose in a baby's system may delay lung maturation and cause respiratory difficulties in babies. This is more likely if they are born before 37 weeks of pregnancy.
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