what is GBS (group b strep)

An image of GBS.

What is Group B Strep (GBS)?

Group B Strep or GBS, is a bacteria that lives in the intestines, urinary and genital tracts of many healthy people. While normal in the gut for many adults, during childbirth, the baby can be exposed to GBS if it is present in other places in the mother's body. Though generally not serious in adults, it can be life-threatening to a newborn if they are exposed.

Most adults who carry GBS, do not have symptoms, but occasionally will develop an infection, such as a bladder infection or urinary tract infection.

Because of the nature of childbirth, when a mother has GBS present in the vaginal area, the baby can be exposed at the time of birth. GBS is not serious enough that women are recommended to choose cesarean delivery if they test positive for GBS, but certain precautions are often taken to prevent transmission.


The Center for Disease Control (CDC) and the American Congress of Obstetricians and Gynecologists (ACOG) recommend that all pregnant women be screened between 35-37 weeks of their pregnancies to determine if they are carriers of GBS.

To test, the pregnant woman's vaginal and rectal areas are swabbed during the screening. Using what looks like a large cotton swab, either the mother will swab herself or her care provider will swab her during a visit in the last weeks of pregnancy.

According to The March of Dimes and the CDC, approximately 25% of pregnant women are found to be colonized with GBS. Because it takes a few days to get the GBS culture back, women are tested a few weeks before their expected due date rather than at the time of birth.

Symptoms in the Infant:

GBS can manifest in two ways and can cause several different problems.

GBS can occur early (early onset GBS) during the first week of an infant's life. Early onset GBS is the most common. Late onset GBS happens after the first week until the third month.

Both late and early onset GBS can cause blood infections (sepsis), pneumonia, and even meningitis in the newborn, though meningitis is more common in late onset GBS. Though the occurrence of serious illness even in babies whose mother's tested positive, is low, the results can be frightening. Because of this, some kind of preventative treatment is standard.

Babies can also be tested after birth for GBS by taking a blood or spinal fluid sample, if symptoms are suspected.


Options for testing and treating GBS vary depending on birth place and region. In many hospitals the standard treatment for a GBS positive mother is IV antibiotics repeatedly throughout labor. Your care provider will often want at least one dosage of IV antibiotics to be given four hours prior to the birth.

Typically, ampicillin is used, a common antibiotic. About 4% of women have a mild allergic reaction to ampicillin, but serious reactions are uncommon.

Some question the impact the IV antibiotics will have on the newborn baby and the incidence of thrush (or oral yeast) in the newborn and yeast infections in the breast for the new mom. A yeast infection in the breast can be very painful and make breastfeeding difficult for a new mom.

In some parts of the world a Chlorhexidine rinse is done during labor or even before labor to rinse the vaginal area. This is fairly typical in European countries but is not the standard of care in the US.

The World Health Organization discourages over use of antibiotics because of the problems that can result internationally when antibiotic resistant strains of bacteria become more common.

Talk to your care provider about what your options are regarding both the testing and the treatment of group B strep. If birthing in the hospital, discuss with your care provider how you and the baby will be treated.

If you are birthing at home, discuss with your care provider what will happen in case of transfer if you have not been tested for GBS.

Be sure to further research the likelihood of transfer to the baby and the known risks to the baby of standard treatment. There are no easy answers or guarantees with GBS.

Image credit: By CDC (Centers for Disease Control and Prevention) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons

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