Group B Streptococcus (GBS)
What is Group B Streptococcus?
GBS is a bacteria (gram-positive) commonly found in the genital and gastrointestinal tracts of adults. These areas include the intestines, rectum, vagina and urinary tract. It is possible for GBS to be transferred from the birthing parent to the baby during the birthing process. The baby may acquire the bacteria while passing through the birth canal or via ascending infection up into the uterus after the waters have broken.
Approximately 15% to 40% of pregnant people will have GBS present in their body at any given time, indicating they are ‘GBS positive’ (AOM 2022). GBS is not a sexualy transmitted infection and has nothing to do with hygiene. As GBS is a transient bacteria (meaning it comes and goes) the test for GBS is not performed until the last few weeks of pregnancy.
How do I know if I have GBS?
Your midwife will offer you a self swab test for GBS between 35 to 37 weeks of pregnancy. This test is performed by you at our clinic and then sent to the lab for results. Your midwife will inform you how to perform the self swab prior to giving it to you. When GBS is present in very high numbers, it is also possible to detect through a urine sample. However, this method of detection is generally only used when screening for urinary tract infection, not for the sole purpose of determining GBS status.
How does GBS affect my baby?
As previously mentioned, it is possible for the babies of ‘GBS positive’ clients to pick up the bacteria during the birthing process. It is also possible for GBS bacteria to ascend into the uterus after the waters have broken. The amniotic sac generally acts as a protective barrier for babies, however, once the waters have broken there is a direct pathway for GBS bacteria to pass through the vagina into the uterus.
The majority of babies who pick up GBS bacteria will not become sick, the bacteria will only live on their skin. However, a small number of babies can develop a serious infection called early-onset group B streptococcus disease (EOGBSD). For these babies the bacteria could potentially get into their blood (bacteremia), lungs (pneumonia) or brain/spine (meningitis).
Statistics regarding GBS and EOGBSD infection (AOM 2022):
- 15% to 40% of pregnant people are GBS positive
- 40% to 70% of babies born to GBS- positive pregnant people will be colonized (pick up the bacteria) if untreated
- 1% to 2% of colonized babies will develop EOGBSD if untreated
- 5% of babies who develop EOGBSD will die
How to reduce the risk of EOGBSD for my baby?
The treatment recommendation for GBS-positive clients is to receive IV antibiotics in labour. The antibiotic most commonly used is penicillin. However, there are alternative antibiotic options available for clients allergic to penicillin. Antibiotics are effective in greatly reducing the amount of GBS bacteria present in your body. Because of this reduction in GBS bacteria, your baby will have much less exposure to the bacteria and will be less likely to get sick from it. The antibiotics are most effective if given at least 4 hours before your baby is born. Antibiotics can be given out of the hospital, so the need for antibiotics does not affect your birth location decision. The goal of GBS testing and treatment is always to prevent as many babies as possible from developing EOGBSD.
Please feel free to explore the additional resources listed below and speak to your midwife if you have any questions.