Question: I am now 36 weeks pregnant. I was tested last week and my doctor just told me that I carry something called ‘Group B Streptococcus’ in my vagina. Will this affect my pregnancy and what can I do about this?
Answer: The majority of pregnant women testing positive for Group B Strep (GBS) have no problems, But GBS can lead to certain complications both in the baby and in you, so when you test positive for GBS in pregnancy, you should get treated in labor.
About one in four pregnant women carry a bacterium called Group B Streptococcus (Group B Strep or GBS) in their vagina. Most don’t even know that they carry it. Women can carry GBS in the bowel, vagina, bladder, or throat, usually without showing any symptoms. It’s no really well established how exactly women get infected with GBS, but it could be sexually transmitted and people who carry GBS typically do so temporarily that is, they do not become lifelong carriers of the bacteria.

In pregnant women, GBS can cause bladder infections and womb infections in the mother. It can also infect the fetus before or during birth though infection of the fetus is rare and happens in less than one of every 100 babies whose mothers carry GBS.

Babies that become infected with GBS at birth (“early-onset”) can develop pneumonia or meningitis, an infection of the nervous system. Babies that survive the initial infection, particularly those who have meningitis, may have long-term problems, such as hearing or vision loss or learning disabilities. Premature babies are more susceptible to GBS infection than full-term babies, but three in four babies who get GBS disease are full term.

GBS disease may also develop in infants 1 week to several months after birth ("late-onset disease"). While the source of the infection in early-onset disease is usually the mother, in late-onset disease the source of the infection is usually unknown.

Infections with GBS can be successfully treated with antibiotics (e.g., penicillin or ampicillin) given through a vein.

Testing for GBS is easy. It can be detected by taking a swab of both the vagina and rectum for special culture, which may take up to a week to return results. The Centers for Diseases Control (CDC) have suggested routine testing for GBS at 36-38 weeks of pregnancy. 

Pregnant woman that test positive for GBS should be  treated with antibiotics (usually Penicillin) in labor. A positive GBS culture result means that the mother carries GBS. It does not mean that she or her baby will definitely become ill.

Women who carry GBS have a relatively low risk of delivering an infant with GBS disease. And all women who are found to carry GBS in the urine should get treated both at the time the diagnosis is made and in labor.

Treating GBS positive women without symptoms before labor doesn’t work well because it does not effectively remove the bacterium.