What Is GBS?

Group B streptococcus (GBS) is a type of bacteria that can be found in many parts of the human body, including in the vagina and rectum (bottom). GBS is a "transient bacteria," meaning it can come and go; one month you may have GBS in your body, and the next month it may be gone. You generally don’t know it's there as it rarely causes any harm in healthy adults.

However, if you have GBS in your vagina or rectum at the time you go into labour, it can be passed to your baby and sometimes, but rarely, will make the baby very ill. If this happens it is called "early onset GBS infection" or "EOGBS" and will cause the baby to get sick within the first 7 days of life. EOGBS in the newborn can cause infections such as pneumonia. In rare cases, EOGBS infection in newborns can cause death.

Up to 30 percent of individuals will test positive for GBS, meaning they do have it. 50 percent of babies born to these individuals will get GBS bacteria on or in them (colonized). This in itself causes no symptoms or problems for 98-99 percent of babies. However, the other 1-2 percent of babies who get colonized by GBS may become ill with early onset GBS infections. 

Luckily, GBS infection is rare. The number of babies that get ill from EOGBS has dropped from 1-2 in every 1,000 births (0.01-0.02 percent) in the 1990s to 0.35-0.5 in every 1,000 births now (0.035-0.005 percent).

Although the risk of EOGBS infection is very rare, some babies do die if they get it. The number of babies that die from EOGBS infection has dropped significantly, from 70 percent of those who got sick from EOGBS in the 1990s to less than 3 percent now.

To reduce the risk of EOGBS in your newborn, your care provider will offer you a test in the form of a swab, which is like a long Q-tip, to check if you have GBS. This test is usually done between 35 to 37 weeks of pregnancy. If this routine swab result is positive for GBS (meaning you do have it), in order to reduce the risk of your baby getting ill from GBS, it will be recommended that you receive intravenous (IV) antibiotics during your labour and delivery, usually penicillin.

However, if your routine swab is negative for GBS (meaning you do not have it) then it would not be recommended for you to have IV antibiotics for GBS (although you might be recommended to have them for other reasons). Other reasons antibiotics in labour for GBS would be recommended is:

  • You've had a previous baby that had a GBS infection
  • You had GBS in your urine at any point in your pregnancy
  • You go into labour prematurely (less than 37 weeks gestation)
  • Your GBS status is unknown when you go into labour and your waters have been broken for a prolonged time (18 hours or longer) and/or you start running a fever in labour

This is what is called "the standard of care" for all pregnant individuals in Canada. If you choose to participate in this study, the standard of care will not change.

Currently there is no recommended standard of care for preventing or reducing the chance of GBS colonization in pregnancy.