Screening for Gestational Diabetes and Group B Strep

Gestational diabetes

Gestational Diabetes is a condition of elevated blood glucose which is first recognized during pregnancy. It affects 3-5% of all pregnancies. It is caused by rising levels of pregnancy related hormones which interfere with the body’s ability to control blood glucose levels.

Screening For Gestational Diabetes

Mothers are screened between 24-28 weeks with a 1 hour glucose test. You do not need to fast for this test. You will be asked to drink a 50g glucose solution (Glucola) and your blood will be drawn one hour later. Approximately 15% of patients will have a positive test and will be asked to take the 3 hour glucose tolerance test (GTT).

Three hour Glucose Tolerance Test (GTT)

In order to prevent false positive results (in other words to maximize your chance of passing the 3 hour GTT) you will need to prepare yourself by including at least 150g of carbohydrates in your diet per day for the three days prior to your test (see table of foods containing carbohydrates below).

After an overnight fast, we will draw a blood test to check your fasting glucose and then have you drink 100g glucose solution and then redraw your blood in 1, 2 and 3 hours.

Approximately 15% of patients who take the three hour GTT will test positive for gestational diabetes.

Gestational Diabetes

If you are diagnosed with gestational diabetes you will meet with a dietician who will help put you on a diabetic diet in which careful calorie counting and avoidance of certain foods are emphasized. Usually that is all that is needed to control your blood glucose. A small percentage of patients will need additional insulin therapy to control their diabetes.

We will order a few more ultrasounds to follow your baby’s growth. If you do require insulin, we will monitor your baby with nonstress tests in the third trimester.

Babies born to mothers who develop diabetes during pregnancies are not at increased risk for birth defects. Your baby is at increased risk for less serious conditions such as macrosomia (being large at birth), hypoglycemia (low blood glucose), and hyperbilirubinemia (jaundice).

If you are told that you need the three hour glucose test you must fast as of 10:00PM the night before the test.

List of Carbohydrates

Each item on the list contains approximately 15g carbohydrate

1/2 cup cereal 1 baked potato 1 slice pound cake
1/3 cup rice 1/2 cup mashed potato 1 apple
1/2 cup pasta 1/2 bagel 9 inch banana
1/4 cup baked beans 1 slice bread of any type 3/4 cup of blueberries
1/2 cup corn 3 graham crackers 1 and 1/4 cup strawberries
1/2 cup peas 6 saltine crackers 1 and ¼ cup cubed watermelon
12 cherries 15 grapes 1 orange
1 pear ½ cup most fruit juices 1 and 1/4 cup milk (Skim or whole)

Group B Beta Hemolytic Strep

What is GBBS?

Group B Beta Strep is a bacteria found commonly in genital and rectal tracts of females.  It is a normally occurring bacterium, typically causing few to no side effects.  Many women do not know they have GBBS until they are tested in pregnancy.  Typically, testing for GBBS is performed around your 36week visit, however, some women may test positive for GBBS in urine testing done throughout the pregnancy.  If you test positive for GBBS in your pregnancy, regardless of when you test positive and any treatments you receive, you will be given antibiotics through your IV during labor. 

How did I get GBBS?

The exact cause of transmission/acquisition of GBBS is unknown.  GBBS is a common bacteria present in approximately 30-40% of women.  Partners do not need to be treated for GBBS exposure.

Why do I need to be treated for GBBS?

Women found to be positive for GBBS in pregnancy will be treated during labor to decrease the transmission of GBBS to the baby during delivery.  If you are found to have GBBS in your vagina or urine earlier in the pregnancy you will receive oral antibiotics during pregnancy as well as during labor.

Will I ever test negative for GBBS?

Women who test positive for GBBS in one pregnancy may test negative in the next pregnancy or in any subsequent exams.  It is not necessary to continue treatment or repeat testing for GBBS after delivery. 

Will my baby need any other testing because I am positive for GBBS?

In certain circumstances the baby may be tested for GBBS or given antibiotics after delivery for exposure to GBBS.  Many factors are involved in making the decision to test or treat the baby.  This decision will be at the discretion of your pediatrician.

Click here for more information on Group B Strep in pregnancy