Approximately 7 percent of the 4 million women who give birth each year in the United States develop gestational diabetes. Researchers don’t know why some women develop gestational diabetes. To understand how gestational diabetes occurs, it can help to understand how pregnancy affects your body’s glucose processing.
Your body digests the food you eat to produce sugar (glucose) that enters your bloodstream. In response, your pancreas, a large gland behind your stomach, produces insulin. Insulin is a hormone that helps glucose move from your bloodstream into your body’s cells, where it’s used as energy. During pregnancy, the placenta, which connects your baby to your blood supply, produces high levels of various other hormones. Almost all of them impair the action of insulin in your cells, raising your blood sugar.
Modest elevation of blood sugar after meals is normal during pregnancy. As your baby grows, the placenta produces more and more insulin-counteracting hormones. In gestational diabetes, the placental hormones provoke a rise in blood sugar to a level that can affect the growth and welfare of your baby. Gestational diabetes usually develops during the last half of pregnancy, sometimes as early as the 20th week, but generally not until later.
There are some risk factors that can increase your chance of getting gestational diabetes. These include:
• Age greater than 25.
• Family or personal health history. Your risk of developing gestational diabetes increases if you have pre-diabetes, slightly elevated blood sugar that may be 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 (4.1 kilograms) or if you had an unexplained stillbirth.
• Excess weight. You’re more likely to develop gestational diabetes if you’re significantly overweight with a body mass index (BMI) of 30 or higher.
• Nonwhite race. For reasons that aren’t clear, women who are black, Hispanic, American Indian, or Asian are at higher risk to develop gestational diabetes.
There are also increases in complications that can affect the baby. Extra glucose in your bloodstream crosses 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, those that weigh 9 pounds or more, are more likely to become wedged in the birth canal, sustain birth injuries, or require a C-section birth. A mother’s high blood sugar may also increase her risk of early labor and delivering her baby before the baby’s due date. However, babies may experience respiratory distress syndrome even if they’re not born early.
Sometimes babies of mothers with gestational diabetes can develop low blood sugar (hypoglycemia) shortly after birth because their own insulin production is high. Severe episodes of hypoglycemia may provoke seizures in the baby. Babies of mothers who have gestational diabetes have a higher risk of developing obesity and type-2 diabetes later in life. Untreated gestational diabetes can result in a baby’s death either before or shortly after birth.
Women with gestational diabetes are at higher risk for gestational hypertension and preeclampsia, a serious complication of pregnancy that causes high blood pressure and other symptoms that can threaten the lives of both mother and baby. These women are also at risk for a cesarean delivery and have a 7-fold increased risk of developing diabetes later in life.
There are no guarantees when it comes to preventing gestational diabetes, but the more healthy habits you can adopt before pregnancy, the better. If you’ve had gestational diabetes, these healthy choices may also reduce your risk of having it in future pregnancies or developing type-2 diabetes down the road. Women should choose foods high in fiber and low in fat and calories. Focus on fruits, vegetables, and whole grains and watch portion sizes.
Exercising before and during pregnancy can help protect you from developing gestational diabetes. Aim for 30 minutes of moderate activity on most days of the week. Finally, lose excess pounds before pregnancy. Doctors don’t recommend weight loss during pregnancy. But if you’re planning to get pregnant, losing extra weight beforehand may help you have a healthier pregnancy.
Testing for gestational diabetes is based on first screening with the administration of 50 g of an oral glucose solution followed by a 1-hour blood draw. Those women meeting or exceeding the screening threshold undergo a 100-g, 3-hour diagnostic oral glucose tolerance test (OGTT). This testing is normally done between 24 and 28 weeks’ gestation in all pregnant women. Women who fail 2 out of the 4 values on their 3-hour test are diagnosed with gestational diabetes.
The first step of treatment begins with nutrition therapy and surveillance of blood glucose levels. A patient will need to test her blood sugar first thing in the morning while fasting and also one hour after breakfast, lunch, and dinner. Fasting levels should be under 90 while one hour after meals should remain under 140. Exercising after meals can help bring down blood sugar levels.
When adequate glucose levels cannot be consistently achieved through nutrition and exercise, medications are recommended. When pharmacologic treatment of gestational diabetes is indicated, insulin and oral medications are equivalent in efficacy and either can be an appropriate first-line therapy. Also close observation of the baby is recommended. This is done by monitoring baby’s growth and development with repeated ultrasounds or other tests. If a woman doesn’t go into labor by her due date or sometimes earlier, her doctor may induce labor.
After delivery of the baby, gestational diabetes frequently resolves, although up to one third of affected women will have diabetes or impaired glucose metabolism at postpartum screening, which is recommended at 6 to 12 weeks after delivery.
Melissa Waddell, WHNP. is a nurse practitioner at Atlantic Ob/Gyn located in Va. Beach and Chesapeake. Please call 757-463-1234 or visit www.atlanticobgyn.com.