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What is Group B streptococcus (GBS)?

Group B streptococcus (GBS) is one of many bacteria that can naturally exist in your body. GBS is commonly found in the intestines, rectum, urethra or vagina. About 1 in 5 females have it in their vagina and it usually causes no health concerns or symptoms.

This bacterium is transient, meaning that it comes and goes from your body. GBS is not sexually transmitted.

Being a carrier of GBS in pregnancy is not usually harmful to you, but it can cause infection in your baby.

Carrying GBS, also known as GBS colonisation, is not the same as having a GBS infection. When you carry GBS, it means the bacteria are in your body. This doesn’t usually cause illness. A GBS infection is when the bacteria cause illness or symptoms. If you carry GBS during pregnancy, your baby could be at risk of infection during delivery, which can lead to serious problems such as sepsis, or .

What if I am a carrier of GBS during pregnancy?

If you carry GBS while pregnant, there is a small risk of the infection affecting you or your baby. GBS in pregnancy can lead to:

• in your urine — this doesn’t have symptoms and is known as asymptomatic bacteriuria
• urinary tract infection (UTI) or upper genital tract infection
• , known as pyelonephritis
• an infection in the fluid around your baby, called chorioamnionitis
• inflammation of the lining of your uterus, or postpartum endometritis
• a type of lung infection, known as pneumonia
• a serious response to infection known as sepsis

What could GBS mean for my baby?

If you carry GBS, there is a small chance that the bacteria will pass to your baby during birth and that they will develop a GBS infection and become seriously ill.

Most babies who come into contact with GBS during labour or around the time of birth do not become unwell.

If your baby develops an infection in the first week after birth, it is known as ‘early onset GBS infection or sepsis’. The chance of your baby getting sick with early onset GBS infection may be lower if you receive antibiotics during labour.

If a baby develops a GBS infection between one week and 3 months after birth, it is called ‘late onset GBS infection’. Unfortunately, having antibiotics during labour doesn’t prevent your baby developing late onset GBS infection.

In newborn babies, GBS can cause:

• pneumonia
• blood infection (septicaemia)
• meningitis (an infection around the brain)

Some babies who become infected may have long-term disability and sadly some may not survive.

What are the risk factors for early onset GBS infection?

Your baby is more likely to become infected with early onset GBS if:

• you give birth prematurely
• your waters break before 37 weeks of pregnancy
• you give birth more than 18 hours after your waters break
• you have a (over 38°C) while in labour
• you've had a previous child with GBS infection
• a during pregnancy showed GBS
• a swab taken no more than 5 weeks before birth showed GBS

How is GBS diagnosed during pregnancy?

GBS may be found during a routine antenatal test. It can be found in a urine test, or more commonly on a vaginal or rectal swab testing for GBS.

There is no standard practice for testing for GBS in Australia. Many healthcare providers recommend universal screening for GBS. This means that everyone will be offered a swab to test for GBS bacteria during pregnancy. Some healthcare providers do not test routinely for GBS, but instead recommend treatment with in labour if you have risk factors that make GBS infection more likely.

The test can only find GBS if the bacteria is there at the time of testing. Because GBS bacteria comes and goes from your body, routine screening for these bacteria may not detect GBS in everyone who has it during pregnancy.

Testing for GBS involves taking a swab of the inside the vagina and rectum. You can usually do this test yourself, but if you prefer your doctor or midwife can do this for you. Some people who test positive during pregnancy may be negative during labour. The swab is usually taken between 35 to 37 weeks of pregnancy to make sure it is the most accurate and to avoid overtreatment of antibiotics during labour.

Testing for GBS is your choice and it is important that you have enough information to make an informed decision about what is right for you. Speak to your doctor or midwife to understand more about GBS testing and management where you plan to give birth.

How is GBS in pregnancy treated?

If your GBS test is positive, or if you have risk factors as listed above, your doctor or midwife will probably recommend that you have intravenous (IV) antibiotics when your waters break or when labour starts. Having antibiotics is your choice, and your health team will ask before they give you the IV. If your waters break before your contractions start naturally your healthcare team may recommend inducing labour.

The antibiotic usually given is , but other options are available if you are to penicillin. The antibiotics pass through the placenta and into your baby’s blood. This reduces your baby's chances of GBS colonisation and infection.

There is usually no need for screening or treatment with antibiotics for GBS before a planned caesarean, because the baby will not pass through your vagina.

Your midwife or doctor will discuss all treatments options with you. Speak to your midwife or doctor to understand more about testing and treatment of GBS.

Can GBS infection be prevented?

Unfortunately, there is no way to completely prevent GBS infection in babies.

Early detection and treatment with antibiotics during labour may reduce the chance of your baby becoming very unwell in the first few days of their life. Talk to your doctor or maternal health team about protecting your baby.

What happens after the birth?

If you are at risk of GBS infection during labour, your baby should have extra checks for the first couple of days to look for signs of infection. Your baby’s healthcare team will track their heart rate, breathing and temperature to check they are well. The chance of your baby being infected with GBS is very low.

Signs that your baby is not well may include:

• noisy breathing sounds
• difficulty breathing or breathing too fast
• sleepiness and not being interested in feeding
• vomiting
• having trouble keeping their temperature at the right level (being too hot or too cold)
• pale or blotchy skin
• floppy arms and legs

If you notice any of these signs in hospital or at home, it’s important that you contact your healthcare provider straight away.

Resources and support

Read more about to help you decide if you would like to be tested, on The Royal Women's Hospital's website.

If your baby has been unwell with a GBS infection, visit the or call 1300 622 243 (1300 MBABIES) for support.

Looking for information in languages other than English?

NSW Health has information about .

Looking for information for Aboriginal and/or Torres Strait Islander people?

A culturally safe support for Aboriginal and/or Torres Strait Islander parents to be and new parents.

You can find out more about Aboriginal and/or Torres Strait Islander pregnancy health on or watch the .