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Capital & Coast DHB Women's Health Obstetrics & Maternity Service

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Group B Streptococcus and Pregnancy

Group B streptococcus (GBS) is a common bacterium that lives in the body without causing harm to healthy people. Anyone can be a “carrier” for Group B Strep. GBS develops in the intestine, rectum and vagina in about 25% of pregnant women.

  • Group B strep is not a sexually transmitted infection
  • Group B strep does not cause itching, discharge or other symptoms
  • Group B strep is not the same bacteria as other forms of streptococci bacteria, such as those that cause strep throat


Why does GBS matter?
Although GBS does not cause any problems for the woman, it is one of the more common causes of bacterial infection in newborn babies. The baby is exposed to GBS bacteria during the birth, if the bacteria are present in the woman’s vagina at the time of birth. Even if you have GBS, your baby will not necessarily be infected. Many babies are exposed to the bacteria without becoming unwell, 1 in 100 newborn babies of women who are GBS colonised may develop a GBS infection. Giving antibiotics during labour to women at risk of transmitting GBS to their newborn can help prevent significant neonatal infection of their baby.

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This page was last updated at 4:01PM on February 5, 2020.