Health Encyclopedia

Learn About Gestational Diabetes

You’re in your 24th to 28th week of pregnancy, and your doctor wants to test you for diabetes. If you feel fine, you may wonder why he or she ordered the test.  Between 2% and 10% of all pregnant women who did not have diabetes before becoming pregnant will develop persistent high blood sugar while they’re expecting, according to the National Institute of Child Health and Human Development. This is known as gestational diabetes, and you can have it without having obvious symptoms. Diabetes can affect your health and that of your growing baby, so it’s important to learn more about it. 

What is gestational diabetes?

Diabetes is a condition in which there is a problem with the way your body makes or uses insulin. Insulin is the hormone that enables your body’s cells to use glucose, or blood sugar, for energy. In gestational diabetes, the placenta that nourishes the baby produces hormones that can block the body's ability to use insulin, a condition called insulin resistance. To make up for this, the body needs to produce more insulin. Sometimes a woman’s body just can’t make enough. So, the glucose level in her blood stays high, and she develops gestational diabetes.

Gestational diabetes usually develops later in pregnancy, when the baby's body weight is increasing and after the baby's organ systems have been formed. For most women, gestational diabetes goes away after the pregnancy ends, but the risk for developing it with future pregnancies is higher. Occasionally, a pregnancy will uncover pre-existing type 1 or type 2 diabetes, which will continue after the pregnancy.

Health effects

Gestational diabetes does not cause birth defects. Most women with gestational diabetes have healthy, full-term babies. If gestational diabetes is not adequately treated, the extra blood glucose in the mother's blood crosses the placenta, raising the baby's blood sugar. The baby's body makes extra insulin to store the extra blood sugar as fat.

The infants of mothers with uncontrolled gestational diabetes usually are heavier, sometimes more than 9 pounds. These large babies can make delivery more difficult, with possible birth trauma or the need for cesarean section. In addition, the extra insulin in the baby's body can cause very low blood glucose levels at birth. These babies also have higher risk for breathing problems. Keeping your weight gain at the level recommended by your health care provider and keeping your blood glucose under control during pregnancy will help you have a normal weight baby. Larger babies are more likely to be obese during childhood and develop type 2 diabetes later on.

Women with gestational diabetes are more likely to have high blood pressure problems, such as preeclampsia, which can increase the chance of premature birth.

If you have had gestational diabetes, you are more likely to develop type 2 diabetes later in life, especially if you were obese before getting pregnant.  

Prevention and management

Certain factors can increase your risk for gestational diabetes including:

  • Having a parent, brother, or sister with diabetes

  • Being of African-American, American Indian, Asian-American, Hispanic/Latino, or Pacific Islander heritage

  • Being over 25 years of age

  • Being overweight

  • Having had gestational diabetes before or having given birth to a baby weighing more than 9 pounds

  • Having "pre-diabetes" 

Although you can't change your family or age, before you become pregnant, you should try to maintain a body mass index in the normal range 25 or less. Once you are pregnant, getting adequate physical activity and increasing your weight only as much as your doctor recommends can help keep blood glucose levels in the normal range and prevent a large newborn. Losing weight while you’re pregnant, however, can be dangerous for the baby.

Talk with your doctor before starting an exercise program or a diet during pregnancy. If you’re diagnosed with gestational diabetes, work with your doctor to control your blood glucose by following the meal and exercise plan he or she recommends. If these 2 things don’t help, your doctor may prescribe regular insulin injections to help protect your health and your child’s.