The Association of Ontario Midwives

The Association of Ontario Midwives

Group B strep (GBS)

What Do I Need to Know?  

The purpose of this information is to explain:

  • Group B Streptococcus (GBS)
  • How to find out if you have GBS
  • Factors that increase the chance your baby will have GBS disease
  • What choices you have to lower the chance that your baby will become sick due to GBS in their first seven days of life (known as early-onset GBS disease)

This handout does not tell you about:

  • How GBS causes sickness in newborn babies
  • GBS disease that happens after the first seven days of your baby’s life (known as late-onset GBS disease)

This information can help you make choices about your care. It does not replace the advice you receive from your midwife about your own   situation. 

What is GBS? 

  • GBS is short for Group B Streptococcus, one of many kinds of bacteria that normally live in our bodies.
  • Most people who have GBS have no symptoms and it is not usually harmful to the majority of people.
  • It is unknown why some people carry GBS and others do not.
  • 10% to 35% of people who are pregnant will have GBS in their vagina and/or rectum at any time.
  • GBS is a type of bacteria that lives in our bodies at different times. If we test different people to see if the bacteria is there over a certain time period, we might find it is always there, never there, or sometimes there.

What could GBS mean for my baby?

  • GBS may cause sickness in babies within the first seven days of life (called early-onset disease) or after 7 days (called late-onset disease). This information focuses on the prevention of early-onset GBS disease.
  • The most common way for babies to get GBS bacteria is from their mothers during labour.
  • The majority of babies born to mothers with GBS are not affected by the bacteria. However, a very small number of these babies will develop a GBS infection.
  • GBS can cause bacteria to enter the blood (bacteremia), lung infection (pneumonia), inflammation in the brain and spine (meningitis), respiratory infections and death.
  • One study showed that 30%-50% of infants with early-onset GBS disease had long-term problems (this means 50% to 70% of infants with early-onset GBS disease had no long-term problems).
  • Some babies with early-onset GBS disease may have long-term effects such as mild to severe delays in mental function (cognitive delays), paralysis of all four limbs (quadriplegia) or deafness. 

What increases my baby's risk of getting early-onset GBS disease? 

Your baby is more at risk of getting sick with early-onset GBS disease when one or more the following happens: 

  • you are GBS positive during labour
  • your baby is born before 37 weeks (also called preterm)
  • your baby weighs less than 2500 g (low birth weight)
  • your water breaks more than 18 hours before the baby is born
  • you get a fever during labour (≥ 38°C)
  • you had a previous baby with GBS disease
  • you have GBS in your urine during pregnancy

How can I find out if I carry GBS? 

  • At 35 to 37 weeks of pregnancy, you will be offered a test for GBS.
  • Because GBS can come and go in human bodies, you are offered this test near the end of your pregnancy. This way the test can most likely show whether or not you have GBS in your body when you have your baby.
  • You can do the test yourself or your midwife can do it for you. It is just as accurate for you to do your own test as for the midwife to do it. If you choose to do the test yourself, your midwife will explain how to do it.
  • The test for GBS involves passing a cotton swab, like Q-Tips, inside your vagina and rectum. Your midwife will send the swab to a lab for testing.
  • If your test shows you carry GBS, you are considered GBS positive. If you test shows you do not carry GBS, you are considered GBS negative.
  • No test is 100% accurate. The test may say you are negative when you are positive or say you are positive when you are actually negative for GBS. This test correctly identifies when someone has GBS 87% of the time.
  • If you do not receive this test or choose not to take the test, you will be considered GBS “unknown.”

What is the most effective way to prevent early-onset GBS disease in my baby? 

  • If your baby is considered at risk of developing early-onset GBS disease, you will be offered IV (in the vein) antibiotics during the active stage of your labour.
  • You will receive antibiotics through an IV every four to eight hours (depending on the type of antibiotics you get) until your baby is born.
  • Your midwife can offer most antibiotics at either a home or hospital birth.

What are the risks of getting antibiotics?

  • Antibiotics can cause rare but serious health problems for you and your baby.
  • Relatively common side-effects of antibiotics include: yeast infections for you and your baby and minor allergic reactions to penicillin, such as rash.
  • Other less common side-effects of antibiotics may include: serious allergic reactions to penicillin, the growing number of GBS bacteria that are resistant to antibiotics, other bacteria-related illnesses in babies, and possibly an increased chance your baby will develop asthma or allergies.

What are my choices?

The two most common ways of screening for and treating GBS are: 

1) Everyone takes the test and takes antibiotics if they are GBS positive. 

  • This option is currently used by most care providers in Canada.
  • With this choice, you will be offered antibiotics during labour if you tested positive for GBS between 35 to 37 weeks of pregnancy.
  • With this choice, about 31% of women receive antibiotics in labour.
  • This choice reduces early-onset disease in babies by 65% to 86% when compared to babies of mothers who do not receive antibiotics.

2) Everyone takes the test and takes antibiotics only if they are GBS positive and if there is another risk factor. 

  • With this choice, you will be offered antibiotics during labour if:
    • you tested positive for GBS at 35 to 37 weeks and
    • you go into labour early, develop a fever during labour, or your water breaks before labour.
  • With this choice, about 3.4% of women receive antibiotics during labour.
  • This choice reduces early-onset GBS disease in babies by 51% to 75% when compared to babies of mothers who do not receive antibiotics.
  • Some women will choose not to swab and be GBS "unknown"
    If you are GBS "unknown"
    • you will be offered antibiotics if one or more of the following happens:
      • your baby is born before 37 weeks
      • you develop a fever during labour
      • your water breaks more than 18 hours before the baby is born
      • you had a previous baby with GBS disease
      • you have GBS in your urine during pregnancy

    This handout is developed to keep you informed about GBS screening and management.

    It is your choice: whether you want to test for GBS at all and what options to take if you test positive.

    Please speak with your midwife for more information about GBS.

This information is also available in these languages: Arabic, Farsi, French, Korean, Russian, Simplified Chinese, Spanish, Urdu.