Diabetes in Pregnancy

• What risks does pregestational diabetes pose to the baby?
• What risks does gestational diabetes pose to the baby?
• Does diabetes cause other pregnancy complications?
• What causes gestational diabetes?
• Who is at risk of gestational diabetes?
• How are women tested for gestational diabetes?
• What diet is recommended for pregnant women with diabetes?
• Should a pregnant woman with diabetes exercise?
• Do pregnant women with diabetes require insulin treatment?
• How can a pregnant woman monitor her diabetes at home?
• What tests are recommended to detect pregnancy complications?
• Do women with diabetes require special care after delivery?
• What can a woman with diabetes do before pregnancy to reduce the risks to her baby?
• For further information
• References

Diabetes is a disorder in which the levels of sugar in the blood are too high. This occurs because the body doesn't produce enough insulin or can't use insulin properly. Insulin is a hormone made by the pancreas that lets the body turn blood sugar into energy or store it as fat.  

In untreated diabetes, high blood-sugar levels can damage organs, including blood vessels, nerves, eyes and kidneys. Some people with diabetes need daily insulin injections to prevent these complications.  

About 1 in 100 women of childbearing age has diabetes before pregnancy (pregestational diabetes) (1). Another 4 percent develop diabetes during pregnancy (gestational diabetes) (2).  Most of these women can look forward to having a healthy baby. While diabetes poses some risks in pregnancy, advances in care have greatly improved the outlook for these pregnancies.  

What risks does pregestational diabetes pose to the baby?
Poorly controlled pregestational diabetes poses a number of risks to the baby. These risks can be greatly reduced with good blood-sugar control starting before pregnancy.

• Birth defects: Women with poorly controlled diabetes in the early weeks of pregnancy are 3 to 4 times more likely than nondiabetic women to have babies with serious birth defects. These include heart defects or neural tube defects (NTDs) (birth defects of the brain or spinal cord) (1).
• Miscarriage: High blood-sugar levels around the time of conception may increase the risk of miscarriage (1).
• Premature birth (before 37 completed weeks of pregnancy) (1): Premature babies are at increased risk for health problems in the newborn period as well as lasting disabilities.
• Macrosomia: Women with poorly controlled diabetes are at increased risk of having a very large baby (10 pounds or more). Macrosomia is the medical term for this. These babies grow so large because some of the extra sugar in the mother's blood crosses the placenta and goes to the fetus. The fetus then produces extra insulin, which helps it process the sugar and store it as fat. The fat tends to accumulate around the shoulders and trunk, sometimes making these babies difficult to deliver vaginally and putting them at risk for injuries during delivery.
• Stillbirth: Though stillbirth is rare, the risk is increased with poorly controlled diabetes (3).
• Newborn complications: These include breathing problems, low blood-sugar levels and jaundice (yellowing of the skin). These complications can be treated, but it's better to prevent them by controlling blood-sugar levels during pregnancy.
• Obesity and diabetes: Babies of women with poorly controlled diabetes may be at increased risk for developing obesity and diabetes as young adults (1).  

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What risks does gestational diabetes pose to the baby?
Babies of women with gestational diabetes usually face fewer risks than those of women with pregestational diabetes. Babies of women with gestational diabetes usually do not have an increased risk of birth defects (4). However, some women with gestational diabetes may have had unrecognized diabetes that began before pregnancy. These women may have had high blood sugar in the early weeks of pregnancy, which increases the risk of birth defects.  

Like pregestational diabetes, poorly controlled gestational diabetes increases the risk of macrosomia, stillbirth and newborn complications, as well as obesity and diabetes in young adulthood (4, 5).  

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Does diabetes cause other pregnancy complications?
Women with diabetes (pregestational and gestational) are likely to have an uncomplicated pregnancy and a healthy baby, as long as blood-sugar levels are well controlled. However, women with poorly controlled diabetes are at increased risk for certain pregnancy complications. These include:

• Preeclampsia: This disorder is characterized by high blood pressure and protein in the urine. Severe cases can cause seizures and other problems in the mother and poor growth and premature birth in the baby.
• Polyhydramnios: This is a condition where the mother makes too much amniotic fluid. Polyhydramnios can increase the risk for preterm labor and delivery (1).
• Cesarean delivery: When the baby grows too large, a cesarean delivery often is recommended (5).  

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What causes gestational diabetes?
Gestational diabetes occurs when pregnancy hormones or other factors interfere with the body's ability to use its insulin. An affected woman usually has no symptoms. This form of diabetes generally develops during the second half of pregnancy and goes away after delivery.  

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Who is at risk of gestational diabetes?
Women with certain risk factors are more likely to develop gestational diabetes. These risk factors include (3, 6):

• Had gestational diabetes in a previous pregnancy
• Age over 30
• Overweight and/or excessive weight gain during pregnancy
• Had a very large (over 9 1/2 pounds) or stillborn baby in a previous pregnancy
• One or more family members have diabetes
• African-American, Native American, Asian, Hispanic or Pacific Island ancestry  

However, even women who don't have any risk factors can develop gestational diabetes. For this reason, health care providers screen most pregnant women for the disorder.

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How are women tested for gestational diabetes?
Most pregnant women are screened for gestational diabetes between the 24th and 28th week of pregnancy. Women who are considered at high risk (including women who have had gestational diabetes in a previous pregnancy) often are screened at an early prenatal visit and, if test results are normal, screened again at 24 to 28 weeks.

The test involves consuming a drink that contains 50 grams of glucose (a form of sugar). One hour later, the health care provider takes a blood sample. The sample is sent to the lab to measure the amount of glucose in the blood.  

If the screening test shows that a woman has high levels of glucose in her blood, she will need to take a similar, though longer, test called the glucose tolerance test. This test involves drawing blood samples while the woman is fasting and at 1, 2 and 3 hours after she drinks 100 grams of glucose.

Most women who are diagnosed with gestational diabetes can control their blood-sugar levels with diet and exercise.  

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What diet is recommended for pregnant women with diabetes?
A pregnant woman with gestational or pregestational diabetes should follow a diet designed especially for her. Most women with gestational diabetes are referred to a dietitian for this. A woman with pregestational diabetes should already be following a special diet, but she should get nutritional counseling because she may need to make changes in her diet as her pregnancy progresses.  

The number of calories a pregnant woman with diabetes should eat and the proportion of foods from the various food groups (i.e., grains, proteins, milk products, fruits and vegetables) depends upon many factors, including weight, stage of pregnancy and the baby's rate of growth. A woman's health care provider and dietitian use these factors, as well as her food preferences, in designing a diet.  

Daily calories are usually divided among three meals and about three snacks, including one at bedtime. For a woman with pregestational diabetes, the dietitian most likely recommends a diet that includes (1):

• 20 percent of calories from proteins (including lean meats, poultry, fish, beans, eggs and nuts)
• About 30 to 40 percent from primarily unsaturated fats (fats that come mainly from plants and vegetables)
• 40 to 50 percent from mainly complex carbohydrates (including grains, such as whole-grain bread, cereal, pasta and rice, as well as fruits and vegetables)  

Sweets should be avoided. A similar diet may be recommended for women with gestational diabetes.  

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Should a pregnant woman with diabetes exercise?
Exercise is recommended for most women with gestational diabetes and many women with pregestational diabetes. Exercise can help control diabetes by prompting the body to use insulin more efficiently. However, pregnant women with diabetes always should talk to their health care provider about exercising. Pregnant women with poorly controlled diabetes or certain complications, such as high blood pressure or blood vessel damage (caused by pregestational diabetes), should exercise only with their health care provider's approval.  

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Do pregnant women with diabetes require insulin treatment?
Many women with pregestational diabetes use insulin injections to keep blood-sugar levels under control. During pregnancy, these women usually need to increase their insulin use. Generally, insulin requirements rise most rapidly between about 28 and 32 weeks of pregnancy (1).

Some women with pregestational insulin-dependent diabetes find that an insulin pump (a beeper-sized device that delivers insulin via a tiny plastic tube inserted through the skin) helps improve blood-sugar control.   Some women with pregestational diabetes use oral medications to control their blood-sugar levels. In most cases, these women need to switch to insulin while they are trying to conceive and during pregnancy. Doctors are studying the safety and effectiveness of oral diabetes medications during pregnancy, but until more is known, insulin usually is recommended (1, 7).  

Some women with gestational diabetes are unable to control their blood-sugar levels with diet and exercise. These women are treated with insulin or an oral diabetes medication (glyburide) for the remainder of the pregnancy. Recent studies suggest that glyburide is safe and as effective as insulin in controlling blood-sugar levels in women with gestational diabetes (8, 9).  (Because the women in these studies received the drug after the first trimester, the studies do not demonstrate whether or not treatment is safe to use earlier in pregnancy.)  

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How can a pregnant woman monitor her diabetes at home?
Pregnant women with pregestational and gestational diabetes should monitor their blood-sugar levels several times a day. They use a spring-loaded finger-stick device to obtain a small blood sample, which is placed on a strip and inserted in a meter. This makes it easy to check blood-sugar levels and adjust diet or insulin dosage between prenatal visits.  

The provider may suggest a home urine test to measure levels of ketones. Ketones are weak acids produced when the pregnant woman is not consuming enough calories and her body burns fat instead of blood sugar for energy. Moderate to large amounts of ketones in the urine can be a sign of poorly controlled diabetes and of ketoacidosis, a complication that, unless promptly treated, can lead to death of the fetus. Symptoms of ketoacidosis in the woman may include nausea, vomiting, fruity odor of the breath, breathing problems, mental confusion, and without treatment, coma and even death.  

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What tests are recommended to detect pregnancy complications?
The health care provider carefully tracks the size and well-being of the fetus, especially during the third trimester. The provider may recommend one or more of these tests:

• Ultrasound: This test may be repeated more than once to assure that the fetus is growing at a normal rate. If the baby reaches a weight of 9 pounds, 14 ounces or more, the provider will likely recommend a cesarean delivery at term (1).

• Nonstress test: This procedure monitors the baby's heart rate. It may be repeated weekly or more frequently.

• Biophysical profile: This test combines the nonstress test with an ultrasound exam. It also may be repeated weekly or more frequently.

• Fetal movement counting: Each day the pregnant woman records the number of kicks felt in one or two hours.  

In most cases, these tests show that the pregnancy is progressing normally. Although women with diabetes are at increased risk for cesarean delivery, most have normal vaginal deliveries.

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Do women with diabetes require special care after delivery?
Some women with pregestational diabetes find that their blood- sugar levels may be more difficult to predict in the weeks after delivery. This is especially true if a woman is breastfeeding. Women with pregestational diabetes should monitor their blood-sugar levels frequently, so that they and their health care providers can adjust their dose of insulin or oral diabetes medications.   

After delivery, blood-sugar levels return to normal for most women with gestational diabetes. The American Diabetes Association (ADA) recommends that women who had gestational diabetes have their blood-sugar level checked 6 to 12 weeks after delivery to make sure levels are normal (10). Because women who have had gestational diabetes have about a 50 percent chance of developing diabetes in the future (4), the ADA recommends a blood-sugar check at least every three years (10). These women can help reduce their risk by starting a weight-loss and exercise program after delivery.  

Women who have had gestational diabetes also face up to a 2 in 3 chance of gestational diabetes returning in another pregnancy (2). A weight loss and exercise program after delivery may reduce this risk.  

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What can a woman with diabetes do before pregnancy to reduce the risks to her baby?
Women who have pregestational diabetes or who had gestational diabetes should consult their health care provider before attempting to conceive. Preconception care (care before getting pregnant) can help a woman get her blood-sugar levels under control before pregnancy. This is important because the birth defects associated with diabetes originate in the early weeks of pregnancy, before a woman may realize she is pregnant.  

At a preconception visit, women who are overweight should discuss with their provider how to reach a healthy weight before conceiving. Women who are overweight or obese are at increased risk for gestational diabetes and other pregnancy complications, including high blood pressure, premature delivery, stillbirth, and having a baby with certain birth defects (11). Women who have already had gestational diabetes may be able to reduce their risk in another pregnancy by reaching a healthy weight before their next pregnancy. During pregnancy, women who are obese or overweight should ask their provider about their weight-gain goal; generally, women who are overweight should gain 15 to 25 pounds, and women who are obese should gain 15 pounds (11).  

The provider may recommend that a woman with pregestational diabetes have a blood test that measures glycosylated hemoglobin (a substance formed when glucose in the blood attaches to the hemoglobin protein in red blood cells) every one to two months. This test shows how well blood sugar has been controlled during the past two to three months. It can help determine when it is safest to try to conceive. The test also may be used to monitor blood sugar control during pregnancy. The provider may recommend that a woman who had gestational diabetes have a blood-sugar test to see if her blood-sugar levels have returned to normal, or whether she has developed diabetes.  

All women should take a multivitamin containing 400 micrograms of the B vitamin folic acid, as part of a healthy diet, starting at least one month before pregnancy, to help prevent NTDs. Women with pregestational diabetes are at increased risk of having a baby with an NTD, so taking folic acid may be especially important for them. In some cases, the provider may recommend that the woman take a larger dose (1). Daily doses of 4,000 micrograms have proven successful in reducing the risk of having another baby with an NTD in women who already have had an affected baby.   At a preconception visit, the provider may recommend that women with pregestational diabetes who take oral diabetes medications switch to insulin.  

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For further information
Diabetes Public Health Resource
Centers for Disease Control and Prevention (CDC)  

References

1. American College of Obstetricians and Gynecologists (ACOG). Pregestational Diabetes Mellitus. ACOG Practice Bulletin, number 60, March 2005.

2. American Diabetes Association (ADA). Gestational Diabetes. Accessed 10/11/07.

3. American College of Obstetricians and Gynecologists (ACOG). Your Pregnancy and Birth, 4th edition. ACOG, Washington, DC, 2005.

4. Centers for Disease Control and Prevention (CDC). Diabetes and Pregnancy: Frequently Asked Questions. Accessed 10/11/07.

5. American College of Obstetricians and Gynecologists (ACOG). Gestational Diabetes. ACOG Practice Bulletin, number 30, September 2001.

6. National Diabetes Information Clearinghouse. What I Need to Know About Gestational Diabetes. Accessed 10/11/07. 

7. American Diabetes Association (ADA). Standards of Medical Care in Diabetes, 2007. Diabetes Care, volume 30, supplement 1, January 2007, pages s4-s38.

8. Langer, O., et al. Insulin and Glyburide Therapy: Dosage, Severity Level of Gestational Diabetes, and Pregnancy Outcome. American Journal of Obstetrics and Gynecology, volume 192, January 2005, pages 134-139.

9. Jacobson, G.F., et al. Comparison of Glyburide and Insulin for the Management of Gestational Diabetes in a Large Managed Care Organization. American Journal of Obstetrics and Gynecology, volume 193, number 1, July 2005.

10. American Diabetes Association (ADA). Gestational Diabetes Mellitus. Diabetes Care, volume 27, supplement 1, January 2004, pages s88-s90.

11. American College of Obstetricians and Gynecologists (ACOG). Obesity in Pregnancy. ACOG Committee Opinion, number 315, September 2005.

 

December 2007

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