Between 35 and 37 weeks, you’ll be tested for group B streptococcal—also called group B strep or GBS—and knowing the result is necessary for the health of your baby.If you test positive for group B strep, you are considered a carrier of, or are colonized with, the bacteria.
“Group B strep is a bacteria that usually lives in the GI tract,” says Katie Page, CNM, a certified nurse-midwife at Centra Medical Group Women’s Center. “Ten to thirty percent of women are colonized, so the bacteria sometimes grows in the vagina.”
Bacteria can be passed from mother to baby during delivery. Group B strep disease in newborns can cause sepsis, pneumonia, meningitis, and even death. There is no way to know if you have the bacteria without a test, as the presence of group B strep often causes no symptoms in pregnant women.
The test, which is quick and painless, involves a swab of the lower vagina and rectum, which is then sent to a lab for results. It is a similar process to swabbing the tonsils and the back of the throat to check for strep.
If you do test positive, don’t panic—antibiotics greatly reduce the risk of passing the bacteria to your baby. Penicillin is the preferred drug to prevent group B strep transmission, and there are other options for patients who are allergic to penicillin.
If patients are leery of the group B strep screening test, which is recommended by the Centers for Disease Control and Prevention (CDC) for all pregnant women, Page explains the importance. “With current evidence, the risk to mom or baby from receiving antibiotics during labor is significantly less than the risks to mom and baby from GBS infection. I recommend screening, and treatment for those who test positive,” she says.
If a woman goes into labor before the Group B Strep test can be completed, IV antibiotics are usually given as a preventative measure.
Did You Know?
A pregnant woman who tests positive for group B strep bacteria and gets antibiotics during labor has only a 1 in 4,000 chance of delivering a baby who will develop group B strep disease, compared to a 1 in 200 chance if she does not.
(Source: Centers for Disease Control and Prevention)