Group B streptococcus, or GBS, also known as group B strep, is one of many different bacteria that normally live on our bodies. Approximately one fifth of women “carry” GBS without knowing or having any symptoms.

Group B streptococcus (GBS) is a bacterium that can colonise a pregnant woman’s vagina or rectum. They are normally found in the vagina and/or rectum of between 10% to 25% of healthy, adult women. If given time, GBS can travel upward into the uterus during labour and cause infection in the baby.

How do I know if I carry GBS?
If you carry GBS, you won’t necessarily know as there aren’t usually any symptoms. In most hospitals you will be tested to see if you have GBS in your vagina at around 36 weeks of pregnancy. Some hospitals or doctors will recommend the test for every woman and some may only offer it to women who are considered at high risk.

The test offered is a low vaginal swab, though some doctors may also recommend an anal swab. The test will determine whether the GBS infection is present in your vagina at the time of the test. However, GBS can come and go, so even if you’ve had a positive test earlier in pregnancy, you may not have GBS as you approach delivery.

If you get a positive test result, you will be recommended to have intravenous antibiotics during your labour to reduce the chance that your baby is infected with GBS. The common antibiotic used is penicillin. If you are allergic to penicillins, there are other alternatives such as clindamycin and lincomycin.

Is my baby at risk of developing GBS infection?
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists have identified a number of factors that help to predict whether your baby is more likely to develop early onset GBS infection.

These include if:

  • you go into labour prematurely (before 37 weeks of pregnancy)
  • your waters broke 18 hours or more before you have your baby
  • you have a raised temperature (38 degrees C or higher) during labour
  • you have previously had a baby infected with GBS
  • you have been found to carry GBS in your urine during your current pregnancy

How should my labour and delivery be managed?
If you don’t fall into one of the higher-risk groups, above, your baby is highly unlikely to develop a GBS infection.

If you are higher-risk, research shows that having intravenous antibiotics from the start of your labour or from when your waters break until your baby is born can prevent most GBS infections in newborn babies.

If you have two or more of the above risk factors then your doctor is much more likely to recommend treatment during labour to reduce the risk of your baby developing an infection.