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Not Just Another Test in Pregnancy: Why Group B Strep Matters

Medical professional speaking to patient

Group B beta-hemolytic streptococcus (GBS) is a common type of bacteria that is often found in the reproductive tract, urinary tract or digestive tract of healthy women and men.

This means that the bacteria is supposed to be present in these areas. This bacteria does not usually cause serious illness and most individuals with the bacteria do not show symptoms. One in four adult women will be colonized with GBS vaginally or rectally. GBS is not sexually transmitted.

Why do we Test for GBS During Pregnancy?

A woman who has GBS later in pregnancy can potentially pass GBS on to her baby during child birth. Even though the bacteria is normal for the woman, it can be harmful to the baby, leading to infections in the newborn. GBS affects 1 in every 2,000 babies in the United States. Not every baby who is born to a mother positive for GBS will become ill. However, if infection develops it can be severe. The most common newborn infections associated with GBS are lung infections, blood infections, and meningitis. Therefore, testing for GBS is a vital part of routine prenatal care. Treatment of maternal GBS during labor can help prevent newborn GBS associated infections.

How will I Know if I Have GBS?

Routine screening for GBS is recommended for all women during each pregnancy. The test is performed between 35 and 37 weeks of pregnancy and involves a swab of both the vagina and rectum. This test is quick and not painful. Because women typically do not have symptoms associated with the presence of GBS, all pregnant women are tested.

What Happens if my GBS Test is Positive?

If a woman tests positive for GBS during her pregnancy, she will receive antibiotics during labor and delivery to prevent GBS from being passed to the newborn baby. The antibiotics must be given during labor as the bacteria may recur if treated too early. Penicillin is the most common antibiotic used to treat GBS but alternatives are available if you are allergic to this.