What is gestational diabetes, and why does it develop?

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When blood sugar, or blood glucose, levels rise too high during pregnancy, the medical name for this is gestational diabetes. The hormonal changes that can cause it usually begin around the 20–24th week of pregnancy, in the second trimester.

A doctor usually tests for the condition between the 24th and 28th week of pregnancy.

Excessive levels of glucose in the bloodstream could cause complications for the pregnant person and their unborn baby. This is why it is important that a doctor diagnoses gestational diabetes promptly to ensure that blood glucose levels are stable.

Around 2–14% of pregnant women in the United States develop gestational diabetes.

Blood sugar levels usually return to normal after the baby is born, though about 50% of women who experience gestational diabetes may develop type 2 diabetes in the future.

Insulin resistance can lead to gestational diabetes. Though the body still produces insulin, the hormone is no longer effective at reducing blood sugar levels.

Hormones released from the placenta interfere with how well insulin can store glucose in fat and muscle cells. As a result, levels of glucose in the blood rise.

During pregnancy, all women experience some insulin resistance. Usually, the body produces additional insulin to compensate.

However, when a person has gestational diabetes, the body typically does not produce enough insulin to overcome insulin resistance.

Gestational diabetes usually does not cause symptoms. But it may cause increased thirst, and a person may notice that they need to urinate more than usual.

Anyone who experiences concerning symptoms during pregnancy should contact a healthcare professional, no matter how subtle the symptoms are. People’s experiences of pregnancy vary. The changes could be a regular part of the pregnancy’s progression, but if a person is worried, it is important to receive medical advice.

The goal of treatment is to manage blood glucose levels, usually through lifestyle changes.

Dietary recommendations

The American Diabetes Association recommends a healthy diet for managing blood glucose levels.

Pregnant women, in general, should aim for:

• 175 grams (g) of carbohydrates per day
• at least 71 g of protein per day
• 28 g of fiber per day

After receiving a gestational diabetes diagnosis, a person should limit their intake of saturated fats and avoid trans fats altogether.

A healthy diet for someone with diabetes includes:

• foods rich in fiber, such as whole grain pasta or brown bread
• fish or poultry instead of fatty and processed meats
• plenty of vegetables and whole fruits
• unsalted nuts, seeds, and legumes

It also involves avoiding sweets and other foods high in added sugar.

A doctor can describe the types of fish that pregnant people should avoid due to high levels of mercury. The Food and Drug Administration (FDA) have list to help guide the discussion.

The Centers for Disease Control and Prevention (CDC) recommend tracking carbohydrate levels and using the “plate method” for meal planning. This involves nonstarchy vegetables taking up half of every plate of food.

Before changing the diet, however, it is a good idea to speak with a doctor, registered dietician, or nutritionist about specific amounts of carbs, proteins, and fats to consume.

Learn more about healthy diets for people with gestational diabetes.

Physical activity

Getting regular exercise is another important component of managing blood glucose levels. However, it is especially important for pregnant people to speak with a healthcare professional before doing more physical activity.

Medication

When lifestyle changes are not working, a healthcare professional may prescribe medication to keep blood glucose levels under control. These medications may include insulin.

According to the American Diabetes Association, doctors recommend monitoring blood glucose levels throughout pregnancy. If a person is taking insulin, they may need to monitor more frequently to ensure that the dosage is correct.

Healthy glucose levels for women with gestational diabetes are under:

• 95 milligrams per deciliter (mg/dl) before meals
• 140 mg/dl 1 hour after eating
• 120 mg/dl 2 hours after eating

Doctors check for gestational diabetes between the 24th and 28th weeks of pregnancy using blood tests. These may involve a one- or two-step glucose tolerance test.

The one-step glucose tolerance test requires fasting overnight. A healthcare professional draws blood the next day to get a baseline reading. The person then consumes a drink containing 75 g of glucose. An hour later, a healthcare professional draws blood. They do this again after another hour has passed.

The two-step test does not require fasting. Instead, a person consumes a drink that contains 50 g of glucose, and a healthcare professional draws blood 1 hour later.

If the reading is abnormal, the person may need to do a 3-hour oral glucose tolerance test. This requires fasting. The person then consumes 100 g of glucose, and a healthcare professional draws their blood at 1 hour, 2 hours, and 3 hours afterward.

People with obesity or larger bodies are at risk for gestational diabetes. A person is also at risk if they gain too much weight during pregnancy.

Some other risk factors for gestational diabetes include:

• a family history of diabetes
• previously giving birth to an infant who weighed more than 9 pounds
• having prediabetes
• having polycystic ovary syndrome, or PCOS
• being of African, Hispanic, Latino, American Indian, Alaska Native, Pacific Islander, Native Hawaiian, or Asian American descent

Gestational diabetes affects up to 14% of all pregnancies in the U.S., and about 60% of women with the condition develop another form of diabetes within 10 years after delivery.

While rates of occurrence and outcomes can be disproportionate, the risk of gestational diabetes increases with an increase in body mass index (BMI) across racial and ethnic groups. However, studies have found that even in cases of low BMI among Hispanic and Asian people, there is an increased risk.

A 2019 study compared the prevalence rate of gestational diabetes in Asian women to women of other ethnic backgrounds in a group of 5,562 women who had participated in a previous study conducted in Los Angeles. The study included a secondary component and evaluated whether acculturation had an impact on the outcome.

None of the women involved had type 1 or type 2 diabetes before their pregnancies, and the study adjusted for the known risk factors of the condition. The researchers found the following prevalence rates:

• 15.5% among Asian American women
• 10.7% among Hispanic women
• 9% among non-Hispanic Black women
• 7.9% among non-Hispanic white women

A 2016 study found that the prevalence rate of gestational diabetes among American Indian and Alaska Native people was 8.9%.

However, most studies that discuss gestational diabetes and use racial and ethnic differences for clarity are limited. Further research that considers environmental, behavioral, genetic, and socioeconomic factors, as well as access to healthcare, is necessary.

Gestational diabetes does not typically cause congenital anomalies or abnormalities. This is because the condition develops in the second trimester.

Most of the possible complications are manageable. Still, congenital conditions are associated with poorly controlled blood sugar levels in people who have diabetes before they become pregnant.

Some examples of the complications of gestational diabetes include:

• prematurity
• high birth weight, which can lead to problems with delivery
• in the baby, low blood glucose levels after birth
• in the baby, breathing problems
• miscarriage or stillbirth

Gestational diabetes may also increase the risk of preeclampsia. This condition can develop from high blood pressure during pregnancy. It can be life threatening for the pregnant person and the unborn baby.

People who develop preeclampsia may require an early delivery, which could involve a cesarean delivery.

Having gestational diabetes may also increase the risk of developing type 2 diabetes in later life, so it is important to be aware of the symptoms of this disease.

Learn more about the symptoms of diabetes here.

People with larger bodies or obesity have an increased risk of gestational diabetes. A nutrient-dense diet and regular physical activity are important for maintaining a healthy weight during pregnancy.

However, a person should discuss any potential changes to their diet or physical activity levels with a doctor, especially while pregnant.

Learn more about preventing gestational diabetes here.

Gestational diabetes refers to high blood sugar levels during pregnancy. The condition usually causes no symptoms, but some people have increased thirst or urinate more often.

People with larger bodies or obesity have a higher risk of gestational diabetes and should be mindful of the symptoms while pregnant.

With appropriate treatment, gestational diabetes is manageable. If a person does not receive treatment or make necessary changes, it could lead to serious complications, such as preeclampsia.

In most people with gestational diabetes, blood sugar levels return to normal after the baby is born. Nevertheless, some people who have had gestational diabetes go on to develop type 2 diabetes, so being aware of the symptoms of this condition is important.

Pregnant people should receive prenatal care and attend all the recommended screenings, evaluations, and other appointments.