Pregnancy and Gestational Diabetes

Gestational diabetes is a condition characterized by high blood glucose (sugar) levels that are discovered during pregnancy. About 3%-5% of all pregnant women in the U.S. are diagnosed with gestational diabetes.

What Causes Gestational Diabetes?

Gestational diabetes is the result of some hormonal changes that occur in all women during pregnancy. Increased levels of certain hormones made in the placenta (the organ that connects the baby by the umbilical cord to the uterus and transfers nutrients from the mother to the baby) interfere with the ability of insulin to manage glucose. This condition is called "insulin resistance." As the placenta grows larger during pregnancy, it produces more hormones and increases this insulin resistance.

Usually the mother's pancreas is able to produce more insulin (about three times the normal amount) to overcome the insulin resistance. If, however, the pancreas cannot produce enough insulin to overcome the effect of the increased hormones during pregnancy, sugar levels will rise, resulting in gestational diabetes.

Am I at Risk for Gestational Diabetes?

These factors increase your risk of developing diabetes during pregnancy:

Being overweight prior to becoming pregnant (if you are 20% or more over your ideal body weight)
Family history of diabetes (if your parents or siblings have diabetes)
Being over age 25
Previously giving birth to a baby over 9 pounds
Previously giving birth to a stillborn baby
Having gestational diabetes with a previous pregnancy
Having too much amniotic fluid (a condition called polyhydramnios)

Keep in mind that half of women who develop gestational diabetes have no known risk factors.

How Is Gestational Diabetes Diagnosed?

Gestational diabetes is generally diagnosed between the 24^th and 28^th week of pregnancy when insulin resistance usually begins. If you have had gestational diabetes before, or if your doctor is concerned about your risk of developing gestational diabetes, a test may be performed before the 13^th week of pregnancy.

To screen for gestational diabetes, you will take a test called the oral glucose tolerance test. This test involves quickly drinking a sweetened liquid, which contains 50g of glucose. The body absorbs this glucose rapidly, causing blood sugar levels to rise within 30-60 minutes. A blood sample will be taken from a vein in your arm about 30 minutes after drinking the solution. The blood test measures how the glucose solution was metabolized (processed by the body).

If your test results are not normal, you will have a similar type of diabetes test that requires you to fast (not eat anything) before the test. If this second test yields abnormal results, you have gestational diabetes.