For women who have diabetes before they become pregnant, the risks of complications during pregnancy depend on how long diabetes has been present and whether complications of diabetes, such as high blood pressure and kidney damage, are present.

Gestational diabetes: About 1 to 3% of pregnant women develop diabetes during pregnancy. This disorder is called gestational diabetes. Unrecognized and untreated, gestational diabetes can increase the risk of health problems for pregnant women and their fetus and the risk of death for the fetus. Gestational diabetes is more common among obese women and among certain ethnic groups, particularly Native Americans, Pacific Islanders, and women of Mexican, Indian, or Asian descent. Most women with gestational diabetes develop it because they cannot produce enough insulin, as the need for insulin increases late in the pregnancy. More insulin is needed to control the increasing level of sugar (glucose) in the blood. Some women may have had diabetes before becoming pregnant, but the disease was not recognized until they became pregnant.

Most experts now recommend that doctors routinely screen all pregnant women for gestational diabetes. A blood test is used to measure the blood sugar level.

Risks of diabetes during pregnancy: If diabetes is poorly controlled early in the pregnancy, the risk of an early miscarriage and significant birth defects is increased. Babies born to diabetic women tend to be larger than those born to women without diabetes. If diabetes is poorly controlled, babies may be particularly large. A large fetus is less likely to pass easily through the vagina and is more likely to be injured during vaginal delivery. Consequently, cesarean delivery is often necessary. The fetus's lungs also tend to mature slowly. The risk of preeclampsia (a type of high blood pressure that occurs during pregnancy) is also increased for women with diabetes.

Newborns of women with diabetes are at increased risk of having low sugar, low calcium, and high bilirubin levels in the blood.

Treatment

The risk of complications during pregnancy can be reduced by controlling the level of sugar in the blood. The level should be kept as near normal as possible throughout pregnancy.

If women who have diabetes are planning to become pregnant, doctors advise them to immediately start taking steps to control the blood sugar level (such as following an appropriate diet, exercising, and, if needed, taking insulin) if they have not already done so (see Diabetes Mellitus (DM): Treatment). High-sugar foods are eliminated from the diet, and women should eat so that they do not gain excess weight during pregnancy.

Most pregnant women with diabetes are asked to measure their blood sugar level several times a day at home. Women who have gestational diabetes are usually taught to measure this level with a home blood sugar monitoring device. If blood sugar levels are high, women may need to take insulin.

Controlling diabetes is particularly important late in pregnancy. Then, the blood sugar level tends to increase as the body becomes less responsive to insulin. This effect occurs partly because the enlarging placenta makes hormones that counteract the effects of insulin. A higher dose of insulin is usually needed.

If an early delivery is being considered (for example, because the fetus is large), the doctor may remove and analyze a sample of the fluid that surrounds the fetus (amniotic fluid). This procedure, called amniocentesis, helps the doctor determine whether the fetus's lungs are mature enough to breathe air.

In newborns of women with diabetes, hospital staff members measure blood levels of sugar, calcium, and bilirubin because these newborns often have abnormal levels. The newborns are also observed for symptoms of these abnormalities.

For women with diabetes, the requirement for insulin dramatically drops immediately after delivery. But the requirement usually returns to what it was before pregnancy within about 1 week.

After delivery, gestational diabetes usually disappears. However, many women who have gestational diabetes develop type 2 diabetes as they become older.

Last full review/revision December 2008 by Sean C. Blackwell, MD