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Group B streptococcus and pregnancy

What is Group B streptococcus?

Group B streptococcus (GBS) is a bacterial organism which commonly lives in the bowel of men and women. One in every four women carries it in their vagina.

How do I know if I have GBS?

Most of us are unaware that we have GBS as it can be difficult to detect and normally does not cause any symptoms.

GBS can usually be found by taking a swab from the lower vagina and rectal area. Sometimes it is identified in a urine test: this is called bacteriuria.

How could GBS affect me?

Although the infection risk for women who carry GBS is low, you have a 7 per cent chance of developing an infection of the uterus during or following labour, called chorionamnionitis.

You are unlikely to be at risk from GBS if you have a planned caesarean birth before establishing labour and your membranes remain intact.

How could GBS affect my baby?

If you carry GBS, there is an extremely small chance that your baby may develop a serious blood infection, pneumonia or meningitis which could even lead to death. Early onset group B streptococcus disease (EOGBSD) affects approximately one baby in every 1000. Most babies with EOGBSD develop the infection in the first 24 hours after birth, but it can still occur up to seven days after birth.

Can EOGBSD be prevented?

Early detection and appropriate antibiotic treatment during labour will reduce the risk of infection. Antibiotics can cause side effects so the decision to use them is always considered very carefully.

Is my baby at risk of developing EOGBSD?

Your baby is likely to be at a higher risk of being exposed to GBS and may go on to develop EOGBSD:

  • if you have tested positive for GBS during your current pregnancy
  • if you have tested positive for GBS bacteriuria during your current pregnancy
  • if you have a raised temperature of 38 degrees Celsius (or higher) during labour
  • if you have ruptured membranes for more than 18 hours before the birth of your baby
  • if your baby is born preterm (less than 35 weeks)
  • if you have previously had a baby with EOGBSD.

Treatment for the mother

If you have any of the above risk factors, treatment with antibiotics is recommended during labour. The antibiotics will be given to you through a drip (intravenous infusion).

Treatment for your baby

All newborn babies are watched closely for signs of infection, particularly when their mother has any risk factors for EOGBSD. If your baby shows signs of infection the paediatrician will recommend immediate treatment with antibiotics. These antibiotics may be given to your baby through a drip or an injection.

Should I have a test for GBS?

Many Australian maternity hospitals do not recommend routine testing for GBS. In Queensland, it has been agreed that the best way to prevent the transfer of GBS form mothers to babies is to give antibiotics in labour to women with risk factors.

If your doctor does routinely screen for GBS, or you would prefer to be screened, then this should be performed between 35 and 37 weeks gestation. The swab should be taken from the lower vagina and rectal area.

If you receive a positive result for GBS, this result is only reliable for the next five weeks. Screening is not perfect and may not detect GBS in approximately five per cent of women who carry GBS.

Where can I get more information?

Your doctor or midwife can answer any questions you may have about GBS and your baby's risk of developing EOGBSD.

This brochure was originally developed, and used with permission by:

  • Translating Research Into Practice (TRIP) Centre, Mater Research (formerly The Centre for Clinical Studies, Mater Health Services) in collaboration with SANDS Qld
Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-430115
Last modified 09/8/2017.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 13/11/2013
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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