For years, doctors believed that gestational diabetes affected three to five percent of all pregnancies. However, new diagnostic criteria puts the number closer to 10 percent. The condition, which can strike any pregnant woman, usually develops in the second trimester between weeks 24 and 28, and typically resolves after baby is born.
If gestational diabetes is treated and well-managed throughout your pregnancy, "there's no reason you can't deliver a very healthy baby," says Patricia Devine, M.D., perinatologist at New York-Presbyterian Hospital in New York City. But gestational diabetes that goes untreated, or isn't carefully monitored, can be harmful for both mother and baby. Consult our guide for risk factors, signs of gestational diabetes, and treatment options.
Gestational diabetes, or diabetes that is diagnosed during pregnancy in a woman who previously did not have diabetes, occurs when the pancreas fails to produce enough insulin to regulate blood sugar efficiently. "A hormone produced by the placenta makes a woman essentially resistant to her own insulin," Dr. Devine explains.
Serious pregnancy complications include preeclampsia (a serious high blood pressure condition that can be fatal), preterm delivery, and delivery of overweight babies, often via Cesarean section. Some 70 percent to 80 percent of women diagnosed with gestational diabetes in the United States eventually develop type II diabetes.
Gestational diabetes only affects pregnant women. People who have type 1 diabetes, sometimes referred to as juvenile diabetes, are generally born with it. Type 2 diabetes accounts for 95 percent of all cases of diabetes in the U.S.; it occurs in adulthood and is triggered by lifestyle factors such as obesity and lack of physical activity.
It's unclear why some women develop gestational diabetes while others do not. Doctors theorize that genetic predisposition, environmental issues (such as obesity prior to pregnancy), and/or behavioral factors (such as diet and exercise habits) may contribute.
The Centers for Disease Control and Prevention (CDC) reports that 2% to 10% of pregnancies are affected by gestational diabetes. Obesity stands out as the major risk factor for the disease, just like with type 2 diabetes. According to a 2014 CDC study, women who've never been diabetic before but who have high blood sugar during pregnancy can develop gestational diabetes. The Centers found a link between increasing rates of gestational diabetes and a rise in obesity in the U.S.
For women who've gained a significant amount of weight during pregnancy and are "borderline" diabetic, Elizabeth Pryor, M.D., FACOG, recommends discussing with your doctor the development of a diet plan so that you can minimize weight gain for the remainder of the pregnancy. "Women who gain significant weight in pregnancy tend to deliver large babies," said Dr. Pryor. "If your diabetes test is borderline, your doctor may consider repeating it later in pregnancy. Certain things that you can avoid that may help include soda drinks, juices, and ice cream. These are common culprits."
Although the condition can strike any pregnant woman, there are several factors that could increase your chances of developing it. Risk factors include:
Age greater than 25
Family history of diabetes
Obesity prior to pregnancy
History of birthing big babies (over 9 pounds)
High blood pressure
Excess amniotic fluid (called polyhydramnios)
History of unexplained miscarriage or stillbirth
Personal history of gestational diabetes
Being African American, Hispanic, American Indian, Alaska Native, Native Hawaiian, or Pacific Islander
Tendency to drink five or more sugar-sweetened sodas a week (especially before conceiving)
History of gum disease
Many women with gestational diabetes have either no symptoms or very mild symptoms. Possible symptoms include fatigue, excessive thirst, blurred vision, frequent urination, weight loss despite an increased appetite, nausea, and vomiting.
If you've had gestational diabetes in a previous pregnancy, you have a 60 percent chance of developing it again, according to the American Diabetes Association. Additionally, half of all women with a history of gestational diabetes develop type 2 diabetes within 10 years of the onset of their gestational diabetes, so it's important to maintain good exercise and nutritional habits after your baby is born.
Around 20 weeks, pregnant women are given a gestational diabetes test in the form of a standard glucose screening that consists of swallowing a concentrated glucose substance and having blood-sugar levels tested one hour later. If elevated blood-sugar levels are detected, a more thorough glucose tolerance test will be given, which involves an overnight fast, drinking another glucose beverage, and more blood work.
Your doctor will recommend diet modifications, such as limiting carbohydrates, and regular exercise to get the condition under control quickly and normalize blood sugar levels. But some women may require daily glucose testing and more intensive treatment, such as insulin injections.
Also, taking certain supplements—vitamin D and calcium, specifically—may lower blood sugar readings and improve other measures of metabolic health that can suffer with gestational diabetes, according to an Iranian study from 2014. The research, which was published in the journal Diabetologia, compared blood levels of women with gestational diabetes—some of whom had been given vitamin D and calcium supplements, and some of whom were given placebo pills—and found that "fasting blood glucose and cholesterol levels improved" in the supplement group but not the placebo group, according to the New York Times.
The findings come with a caveat, however: "Vitamin D has some toxic effects on women and their babies, so we cannot recommend that all women should take it," said the study's senior author, Ahmad Esmaillzadeh, M.D., an associate professor at the Isfahan University of Medical Sciences. "But we can recommend it for people with gestational diabetes who are vitamin D deficient."
You can help minimize your baby's chances of developing complications by carefully managing your gestational diabetes. The condition can cause a newborn to grow very big in utero (over 9 pounds), which may result in a traumatic delivery in which your baby could be injured. Having a very large baby also dramatically increases your chances of needing a cesarean section.
What’s more, "children of women with gestational diabetes are at risk for developing type 2 diabetes themselves," says Danielle Downs, Ph.D., an associate professor of kinesiology and obstetrics and gynecology at Pennsylvania State University who conducts research on gestational diabetes. But even normal-size babies who are born to mothers with untreated GDM are at greater risk of becoming overweight kindergarteners—and, consequently, overweight adults.