Originally Published Sept 2007
GESTATIONAL DIABETES
Gestational diabetes is a diabetic condition (nearly always temporary) that develops during the third trimester. After delivery, blood glucose levels generally return to normal, although between one-third and one-half of these women develop type ll diabetes within 10 years.
Who Gets Gestational Diabetes?
Estimates for the prevalence of gestational diabetes are generally about 4%. Some studies, however, have suggested significantly higher rates. For example in one German study, 13% of pregnant women were diagnosed with this form of diabetes, including many who did not have any risk factors.
Risk factors include the following:
- Even modest weight gain (11 to 22 pounds) during early adulthood.
- Family history of diabetes.
- Smoking.
- Belonging to African American, Hispanic, or Asian ethnic groups.
- Gaining weight before getting pregnant.
- Being an older mother.
It should be noted that some studies suggest that women who develop gestational diabetes during pregnancy and take progestin-only contraceptives while breast feeding are at high risk for developing full-blown type ll diabetes.
Who Should be Tested for Gestational Diabetes?
A number of expert groups now recommend that nearly all pregnant women be tested for gestational diabetes between their 24th and 28th week. Pregnant women at high risk for diabetes should be tested earlier. The only women who do not need to be tested are those at very low risk. Generally they have the following characteristics:
- Under 25 years old.
- Normal weight.
- No first-degree relatives with diabetes.
- Not belonging to the following ethnic groups: Native American, Hispanic, Asian or African-American.
How Serious Is Diabetes in the Pregnant Patient?
Because glucose crosses the placenta, a woman with diabetes can pass high levels of blood glucose to the fetus. In response, the fetus secretes high level of insulin. Studies indicate that such conditions may effect the developing fetus as soon as it is conceived, placing the unborn child at risk for the following:
- Birth defects.
- Excessive growth of the fetus.
- Delayed lung development.
- Possibly a higher risk for future diabetes and obesity in the child.
In addition to endangering the fetus, diabetes also presents risks to the pregnant woman.
In one German study, 25% of women with gestational diabetes required a cesarean section. (The non-diabetic rate in the study was also high however, 19.6%.)
The most serious potential complications from diabetes are high blood pressure and preeclampsia, a potentially dangerous condition. In one study blood pressure was abnormally high in 6.5% of women with gestational diabetes compared to 1.7% of pregnant women without diabetes. (It should be noted that one study suggested that mortality rates in the pregnant women with gestational diabetes vary widely, and normal rates have been reported in some countries, suggesting that good prenatal care can be fully protective.)
How Is Gestational Diabetes Managed?
Some suggestions for preventing complications include the following:
In most cases, increases in glucose levels can be managed with diet and exercise. Aerobic exercise before and during pregnancy may lower glucose levels and may be protective for women at risk or who have gestational diabetes. (Any pregnant woman should check with her physician before embarking on a vigorous exercise regimen.)
If a woman with gestational diabetes cannot keep her glucose under control with life-style measures, then she usually is given insulin.
Oral sulfonylureas, which are standard agents in type ll diabetes, have not been routinely prescribed because of a higher risk for birth defects and severe hypoglycemia in the newborn. Studies suggest that newer sulfonylurea agents, such as glyburide, however, may be effective and safe alternatives to insulin.
