What is it?
- Gestational diabetes is a type of diabetes that occurs only during pregnancy. Like other forms of diabetes, gestational diabetes affects the way your body uses sugar (glucose) — your body's main source of fuel. Gestational diabetes can cause high blood sugar levels that are unlikely to cause problems for you, but can threaten the health of your unborn baby.
- Any pregnancy complication is concerning, but there's good news. You can manage gestational diabetes by eating healthy foods, exercising regularly and, if necessary, taking medication. Taking good care of yourself can help ensure a healthy pregnancy for you and a healthy start for your baby.
- Fortunately, gestational diabetes is usually short-lived. Blood sugar levels typically return to normal soon after delivery.
For most women, gestational diabetes doesn't cause noticeable signs or symptoms. Rarely, gestational diabetes may cause excessive thirst or increased urination.
Researchers don't yet know exactly why some women develop gestational diabetes. To understand how gestational diabetes occurs, it can help to understand how glucose is normally processed in the body.
Insulin is a substance produced by your pancreas. After you eat, sugar molecules from food — called glucose — flow into your bloodstream. Insulin helps glucose move from your bloodstream into cells in your body where it can be used as energy.
During pregnancy, the placenta that surrounds your growing baby produces high levels of a variety of hormones. Almost all of them impair the action of insulin in the tissues, thereby raising blood sugar. Modest elevation of blood sugar after meals is normal during pregnancy.
As your baby grows, the placenta produces more and more insulin-interfering hormones. In gestational diabetes, the placental hormones provoke a rise in blood sugar to a level that can affect the growth and development of your baby. Gestational diabetes usually develops during the last half of pregnancy — rarely as early as the 20th week, but often not until later in the pregnancy.
Any woman can develop gestational diabetes, but some women are at greater risk. Risk factors for gestational diabetes include:
- Being older than age 25. Women older than age 25 are more likely to develop gestational diabetes.
- Family or personal health history. Your risk of developing gestational diabetes increases if you have prediabetes — a precursor to type 2 diabetes — or if a close family member, such as a parent or sibling, has type 2 diabetes. You're also more likely to develop gestational diabetes if you had it during a previous pregnancy, if you delivered a baby who weighed more than 9 pounds, or if you had an unexplained stillbirth.
- Being overweight. You're more likely to develop gestational diabetes if you're significantly overweight with a body mass index (BMI) of 30 or higher.
- Race. For reasons that aren't clear, women who are black, Hispanic, American Indian or Asian are more likely to develop gestational diabetes.
Most women who have gestational diabetes deliver healthy babies. However, gestational diabetes that's not carefully managed can lead to uncontrolled blood sugar levels and cause problems for you and your baby.
Complications that may affect your baby
If you have gestational diabetes, your baby may be at increased risk of:
- Excess growth. Extra glucose will cross the placenta, which triggers your baby's pancreas to make extra insulin. This can cause your baby to grow too large (macrosomia). Very large babies are more likely to become wedged in the birth canal, sustain birth injuries or require a C-section birth.
- Low blood sugar (hypoglycemia). Sometimes babies of mothers with gestational diabetes develop low blood sugar (hypoglycemia) shortly after birth because their own insulin production is high. Severe episodes of this problem may provoke seizures in the baby. Prompt feedings and sometimes an intravenous glucose solution can return the baby's blood sugar level to normal.
- Respiratory distress syndrome. If your baby is delivered early, respiratory distress syndrome — a condition that makes breathing difficult — is possible. Babies born to women with gestational diabetes have more breathing problems than do those born to women without the problem, even at the same gestational age. Babies who have respiratory distress syndrome might need help breathing until their lungs become stronger.
- Jaundice. This yellowish discoloration of the skin and the whites of the eyes may occur if a baby's liver isn't mature enough to break down a substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells. Although jaundice usually isn't a cause for concern, careful monitoring is important.
- Type 2 diabetes later in life. Babies of mothers who have gestational diabetes have a higher risk of developing obesity and type 2 diabetes later in life.
- Developmental problems. If you have gestational diabetes, your child may have an increased risk of problems with motor skill development, such as walking, jumping, or other activities that require balance and coordination. An increased risk of attention problems or hyperactivity disorders also is a concern.
Rarely, untreated gestational diabetes results in a baby's death either before or shortly after birth.
Complications that may affect you
Gestational diabetes may also increase your personal risk of:
- Preeclampsia. Gestational diabetes increases the risk of preeclampsia, a condition characterized by high blood pressure and excess protein in the urine after the 20th week of pregnancy. Left untreated, preeclampsia can lead to serious or even life-threatening complications for both mother and baby.
- Urinary tract infections. Women with gestational diabetes experience twice the number of urinary tract infections during pregnancy than other pregnant women experience. This is likely due to excess glucose in the urine.
- Future diabetes. If you have gestational diabetes, you're more likely to have it again with a future pregnancy. You're also more likely to develop diabetes — typically type 2 diabetes — as you get older. However, making healthy lifestyle choices such as eating healthy foods and exercising can help reduce the risk of future type 2 diabetes. Of those women with a history of gestational diabetes who reach their ideal body weight after delivery, fewer than 25 percent develop type 2 diabetes.
Your doctor will likely evaluate your risk factors for gestational diabetes early on in your pregnancy. Most women will have a screening test for gestational diabetes sometime during the second trimester of pregnancy.
Routine screening for gestational diabetes
Screening for gestational diabetes is recommended for most women. Medical experts haven't established a single set of screening guidelines. Some question whether gestational diabetes screening is needed if you're younger than 25 and have no risk factors. Others say that screening all pregnant women — no matter their age — is the best way to catch all cases of gestational diabetes.
Your doctor will recommend a screening schedule based on your specific risk factors. For most women with average risk of gestational diabetes, a blood test known as a glucose challenge test is recommended between weeks 24 and 28 of pregnancy. If you're at a high risk of gestational diabetes, your doctor may test you earlier.
- Initial glucose challenge test. You'll begin the glucose challenge test by drinking a syrupy glucose solution. One hour later, you'll have a blood test to measure your blood sugar level. A blood sugar level below 130 to 140 milligrams per deciliter (mg/dL), or 7.2 to 7.8 millimoles per liter (mmol/L), is usually considered normal on a glucose challenge test, although this may vary at specific clinics or labs. If your blood sugar level is higher than normal, it only means you have a higher risk of gestational diabetes. Your doctor will diagnose you after giving you a follow-up test.
- Follow-up glucose challenge tests. For the follow-up tests, you'll be asked to fast overnight and then have your fasting blood sugar level measured. Then you'll drink another sweet solution — this one containing a higher concentration of glucose — and your blood sugar level will be checked every hour for a period of three hours. If at least two of the blood sugar readings are higher than normal, you'll be diagnosed with gestational diabetes.
If you're diagnosed with gestational diabetes
If you're diagnosed with gestational diabetes, your doctor will likely recommend frequent checkups, especially during the last three months of pregnancy. During these exams, your doctor will carefully monitor your blood sugar level. Your doctor may also ask you to monitor your own blood sugar daily, as part of your treatment plan.
If you're having trouble controlling your blood sugar level, you need insulin, or you have other pregnancy complications, you may need additional tests to assess your baby's general health. These tests are designed to assess the function of the placenta. This is because if your gestational diabetes is difficult to control, it may affect the placenta and endanger the exchange of oxygen and nutrients to the baby. One abnormal test result doesn't necessarily indicate a problem. Your doctor may do additional tests to more accurately assess how your baby is doing.
- Nonstress test. Sensors placed on your stomach are connected to a monitor. This test evaluates increases in fetal heart rate that are expected with fetal movement. If they're absent, the fetus may not be receiving enough oxygen.
- Biophysical profile (BPP). This test combines a nonstress test with a fetal ultrasound. Your doctor assesses your baby's movements, breathing and whether a normal amount of amniotic fluid is present. The components assessing fetal activity indicate the baby's oxygen status at the time the test is done. Decreased fluid means your baby hasn't been urinating enough and could indicate that over time the placenta has not been working as well as it should.
- Fetal movement counting. You may perform this simple test at the same time as the nonstress test or the biophysical profile. You simply count the number of times your baby kicks within a certain time frame. Less movement may mean your baby isn't getting enough oxygen.
Blood sugar testing after you give birth
To make sure that your blood sugar level has returned to normal after your baby is born, your doctor will check your blood sugar levels after delivery and again in six weeks. If your test results are normal, it's a good idea to have your diabetes risk assessed at least every three years. If your blood sugar levels indicate diabetes or prediabetes — a condition in which your blood sugar level is higher than normal, but not high enough to be classified as diabetes — talk with your doctor about starting a diabetes treatment plan.