You may have heard of gestational diabetes, but what is this condition? During pregnancy, nutrient metabolism changes to nourish the growing baby. Pregnancy hormones and changes in the metabolism of sugar and the body's response to insulin tend to cause blood sugar to be higher than normal. Sometimes, these levels can become high enough to cause a woman to develop a diabetic condition during pregnancy - gestational diabetes - even though she is not normally diabetic.
Pregnancy Induced Diabetes
Some women develop diabetes for the first time during pregnancy (pregnancy-induced diabetes) and don't have it when they are not pregnant. However, other non-pregnant women might have a diagnosis of "borderline diabetes", or prediabetes, which worsens during pregnancy.
In non-pregnant women with prediabetes, blood sugar levels are in the high range of normal. Then when they are pregnant, the metabolic changes of pregnancy raise their blood sugar levels high enough to tip them into overt gestational diabetes.
Increased Maternal and Fetal Risks
Gestational diabetes can cause severe adverse outcomes to mother and baby.
The maternal complications include:
- An increased risk of hypertension
- A higher rate of pre-eclampsia
- A higher risk of cesarean section
- A risk that severe diabetes may develop
The fetal risks include:
- Hydramnios, which is an excessive amount of amniotic fluid, also know as polyhydramnios
- The baby grows unusually large with excess fat deposits for its gestational age. This can lead to a difficult delivery.
- Hypoglycemia, meaning a condition of low blood sugar after birth
- A slightly higher rate of stillbirth for unknown reasons
- Difficulty breathing and jaundice at birth
Close management and control of blood sugar levels will improve maternal and fetal outcomes. With careful medical care, most diabetic women today can have safe pregnancies, normal births, and healthy babies.
The Hidden Diabetic
Many people are unaware they have diabetes unless their symptoms are severe enough to send them to the doctor. Some women with underlying diabetes will first discover the diagnosis when they are screened and tested for the condition during routine prenatal care. It is helpful to be aware of the following signs and symptoms of diabetes before and after you get pregnant:
- Increased thirst and appetite
- Excessive urination, both in frequency and quantity
- Sugar in the urine
- Protein and ketones in the urine
- Unexplained weight loss or weight gain
Diagnosing Gestational Diabetes by Blood Test
All pregnant women have a routine fasting blood sugar test to screen for gestational diabetes between 24 and 28 weeks. You might be screened earlier if you have risk factors, such as a previous history of gestational diabetes, a previous large baby or a stillbirth, overweight, a family history of diabetes, or there is sugar in your urine at any prenatal visit.
If a screening fasting blood sugar level is high, a doctor or midwife will order other blood sugar testing, which includes the glucose challenge test (GCT) - a followup one-hour screening test, or the two to three-hour oral glucose tolerance test (GTT), or both. These blood tests reflect how well your body metabolizes and handles a sugar load.
The GCT: With the GCT, you drink a 50 gram glucose liquid (a glucose load). Your blood sugar is measured an hour later. If your one-hour post-glucose challenge blood sugar level is 140 milligrams per deciliter (mg/dL) or higher, you have gestational diabetes.
The GTT: This test takes three hours to complete:
- A sample of blood is taken to measure a baseline fasting glucose level.
- You next drink a 100 gram glucose liquid.
- A blood sample is taken again at one, two, and three hours after the drink
- If one or more of your blood sugar level is high, you have gestational diabetes.
Your doctor might choose to order both tests in a two-step approach. Accurate performance and interpretation of the tests is important to avoid a misdiagnosis.
The OGTT or GCT are the standard diabetes tests done during pregnancy but can give false positive results and cause an incorrect diagnosis of gestational diabetes. Some doctors recommend the hemoglobin A1C (or HbA1c) blood test instead as a more reliable test.
The HbA1c reflects the history of your blood glucose control over the past two to three months. The higher the level, the more poorly controlled the blood sugar was during that time. Ask your doctor if this is the preferred test for you.
After Your Diagnosis
If you are diagnosed with gestational diabetes, you will have to make changes in your lifestyle and diet and follow your doctor's recommendations to keep your blood sugar in a normal range. This will decrease the risk to your and your baby.
Your doctor might recommend more frequent prenatal visits, monitoring your blood sugar at home, and consultation with a diabetic nurse and nutritionist. He might also advise early monitoring of your baby with ultrasounds and other fetal testing.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, control of gestational diabetes includes following a healthy diet, physical activity, and taking medications your doctor might prescribe. It is important to eat for gestational diabetes and control your intake of carbohydrates. You will find sample diabetic menus, meal plans, specific calorie plans, and food lists helpful in keeping you organized and on track.
Many women will do well and keep their blood sugar in good control on diet alone. Other women will also need insulin injections to control their blood sugar. Your pregnancy specialists will decide on the best course of treatment based on your history, the results of your blood sugar testing, and how well your blood sugar responds to the recommended management.
Many women with gestational diabetes will return to their baseline blood sugar levels after delivery and not have the problem again. Some will have the condition with each pregnancy. Others will continue with long-term diabetes outside of pregnancy.
Women who develop gestational diabetes are at risk greater for diabetes at some point in their lives. Your doctor will advise how often you should have diabetes screening if your six week postpartum test is normal.
Gestational diabetes puts a woman and her fetus at risk if not well-managed. Stick to your doctor's treatment plan to keep your blood sugar in good control and to avoid pregnancy complications and for the best outcome for your baby.