During a 3-hour glucose tolerance test ... test is performed between 36 to 38 weeks of pregnancy. For this test, the vaginal and rectal areas are swabbed with a soft cotton swab for bacteria.

If the readings are high, they will be advised to undergo an Oral Glucose Tolerance Test. Blood samples are taken while fasting and also during one, 2 and 3 hours after having 100 gms of glucose.

After 3 hours, a normal reading would be less than 140 mg/dL. This test has a similar procedure to the previous one. Your blood sugar is measured 2 hours after drinking the glucose solution.