Gestational diabetes occurs in 14 percent to 25 percent of all pregnancies. Obesity, maternal age, ethnicity and a diabetic family history are all factors that contribute to risk of gestational diabetes. An oral glucose test is performed between 24 and 28 weeks of pregnancy to test for this condition.

Gestational diabetes affects pregnant women whose blood sugar levels are elevated during pregnancy. Women who do not have diabetes outside of pregnancy can get gestational diabetes. Expecting mothers are typically tested as a routine part of medical care.

Women who develop diabetes while they are pregnant suffer from a condition called gestational diabetes or gestational diabetes mellitus, also called GDM. The disease strikes about 5 percent of women who are pregnant, or close to 200,000 a year, according to the National Institute of Child Health and Human Development.

By week 37 of pregnancy, a woman has likely been managing her gestational diabetes for about nine weeks. Blood tests for the condition are performed at the beginning of the third trimester, around 28 weeks.

Hypoglycemia or low blood sugar during pregnancy is a common problem in women with diabetes. This blood sugar complication can occur in pregnant women who have preexisting type 1 or type 2 diabetes or in women who have gestational diabetes -- which is usually diagnosed during the second trimester of pregnancy.

Gestational diabetes is a type of diabetes that only occurs during pregnancy. Gestational diabetes increases your risk of having a more complicated pregnancy; giving birth to a large baby that may require a cesarean section or giving birth to a baby with respiratory problems.