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Prenatal Test: Glucose Screening

What Is a Prenatal Glucose Screening?

Glucose screening checks for gestational diabetes, a short-term form of diabetes that some women develop during pregnancy. It's becoming more common in the United States, affecting about 6% to 7% of pregnancies.

The test is usually done at 24 to 28 weeks, but sometimes earlier if a woman is at higher risk for gestational diabetes.

Why Is Prenatal Glucose Screening Done?

Glucose screenings check for gestational diabetes. It's important to diagnose the condition because it can cause health problems in a newborn baby, especially if it's not treated.

What Happens During a Glucose Screening?

This screening test involves drinking a sugary liquid, followed by a blood test an hour later to check glucose levels. If the level is high, you'll have a glucose-tolerance test. For this test, you'll drink a glucose solution on an empty stomach and have your blood drawn once every hour for 3 hours.

Should I Have a Glucose Screening?

Most women have this test, and if they have gestational diabetes, are treated to reduce the risk to the baby.

When Are Glucose Screenings Done?

Screening for gestational diabetes usually is done at 24 to 28 weeks. Testing may be done earlier for women who are at higher risk of having it, such as those who:

  • have previously had a baby who weighed more than 9 pounds (4.1 kilograms)
  • have a family history of diabetes
  • are obese
  • are older than age 25
  • have sugar in the urine (pee) on routine testing
  • have high blood pressure (hypertension)
  • have polycystic ovary syndrome (PCOS)

When Are the Results Available?

The results are usually available within 1 to 2 days. Ask if your health care provider will call you with the results if they are normal or only if the reading is high (in which case, you'll you need to come in for another test).

Date reviewed: May 2018