Gestational diabetes is a condition characterized by high blood sugar (glucose) levels that is first recognized during pregnancy. The condition occurs in approximately 4% of all pregnancies.
What Causes Gestational Diabetes in Pregnancy?
Almost all women have some degree of impaired glucose intolerance as a result of hormonal changes that occur during pregnancy. That means that their blood sugar may be higher than normal, but not high enough to have diabetes. During the later part of pregnancy (the third trimester), these hormonal changes place pregnant woman at risk for gestational diabetes.
During pregnancy, increased levels of certain hormones made in the placenta (the organ that connects the baby by the umbilical cord to the uterus) help shift nutrients from the mother to the developing fetus. Other hormones are produced by the placenta to help prevent the mother from developing low blood sugar. They work by resisting the actions of insulin.
Over the course of the pregnancy, these hormones lead to progressive impaired glucose intolerance (higher blood sugar levels). To try to decrease blood sugar levels, the body makes more insulin to get glucose into cells to be used for energy.
Usually the mother’s pancreas is able to produce more insulin (about three times the normal amount) to overcome the effect of the pregnancy hormones on blood sugar levels. If, however, the pancreas cannot produce enough insulin to overcome the effect of the increased hormones during pregnancy, blood sugar levels will rise, resulting in gestational diabetes.
What Are the Complications of Gestational Diabetes?
Diabetes can affect the developing fetus throughout the pregnancy. In early pregnancy, a mother’s diabetes can result in birth defects and an increased rate of miscarriage. Many of the birth defects that occur affect major organs such as the brain and heart.
During the second and third trimester, a mother’s diabetes can lead to over-nutrition and excess growth of the baby. Having a large baby increases risks during labor and delivery. For example, large babies often require caesarean deliveries and if he or she is delivered vaginally, they are at increased risk for trauma to their shoulder.
In addition, when fetal over-nutrition occurs and hyperinsulinemia results, the baby’s blood sugar can drop very low after birth, since it won’t be receiving the high blood sugar from the mother.
However, with proper treatment, you can deliver a healthy baby despite having diabetes.
Who Is at Risk for Gestational Diabetes?
The following factors increase the risk of developing gestational diabetes during pregnancy:
- Being overweight prior to becoming pregnant (if you are 20% or more over your ideal body weight)
- Being a member of a high risk ethnic group (Hispanic, Black, Native American, or Asian)
- Having sugar in your urine
- Impaired glucose tolerance or impaired fasting glucose (blood sugar levels are high, but not high enough to be diabetes)
- Family history of diabetes (if your parents or siblings have diabetes
- 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)
Many women who develop gestational diabetes have no known risk factors.
How Is Gestational Diabetes Diagnosed?
High risk women should be screened for gestational diabetes as early as possible during their pregnancies. All other women will be screened between the 24th and 28th week of pregnancy.
How Is Gestational Diabetes Managed?
Gestational diabetes is managed by:
- Monitoring blood sugar levels four times per day — before breakfast and 2 hours after meals. Monitoring blood sugar before all meals may also become necessary.
- Monitoring urine for ketones, an acid that indicates your diabetes is not under control.
- Following specific dietary guidelines as instructed by your doctor. You’ll be asked to distribute your calories evenly throughout the day.
- Exercising after obtaining your health care provider’s permission.
- Monitoring weight gain.
- Taking insulin, if necessary. Insulin is currently the only diabetes medication used during pregnancy.
- Controlling high blood pressure.
Do I Need to Take Insulin for Gestational Diabetes?
Based on your blood sugar monitoring results, your health care provider will tell you if you need to take insulin in the form of injections during pregnancy. Insulin is a hormone that controls blood sugar. If insulin is prescribed for you, you may be taught how to perform the insulin injection procedure.
As your pregnancy progresses, the placenta will make more pregnancy hormones and larger doses of insulin may be needed to control your blood sugar. Your health care provider will adjust your insulin dosage based on your blood sugar log.
When using insulin, a “low blood glucose reaction,” or hypoglycemia, can occur if you do not eat enough food, skip a meal, do not eat at the right time of day, or if you exercise more than usual.
Symptoms of hypoglycemia include:
- Feeling shaky
- Sudden hunger
Hypoglycemia is a serious problem that needs to be treated right away. If you think you are having a low blood sugar reaction, check your blood sugar. If your blood sugar is less than 60 mg/dL (milligrams per deciliter), eat a sugar-containing food, such as 1/2 cup of orange or apple juice; 1 cup of skim milk; 4-6 pieces of hard candy (not sugar-free); 1/2 cup regular soft drink; or 1 tablespoon of honey, brown sugar, or corn syrup. Fifteen minutes after eating one of the foods listed above, check your blood sugar. If it is still less than 60 mg/dL, eat another one of the food choices above. If it is more than 45 minutes until your next meal, eat a bread and protein source to prevent another reaction.
Record all low blood sugar reactions in your log book, including the date, time of day the reaction occurred and how you treated it.
How Much Exercise Is Safe for Gestational Diabetes?
Regular exercise during pregnancy can improve your posture and decrease some common discomforts such as backaches and fatigue. Being fit during pregnancy means safe, mild to moderate exercise at least three times a week. But, regardless of gestational diabetes, every pregnant woman should consult with her health care provider before beginning an exercise program. He or she can give you personal exercise guidelines, based on your medical history.
Since both insulin and exercise lower blood sugar, you should follow these additional exercise guidelines to avoid a low blood glucose reaction:
- Always carry some form of sugar with you when exercising, such as glucose tablets or hard candy.
- Eat one serving of fruit or the equivalent of 15 grams of carbohydrate for most activities lasting 30 minutes. If you exercise right after a meal, eat this snack after exercise. If you exercise 2 hours or more after a meal, eat the snack before exercise.