Group B Strep

Group B Strep (GBS) is a common bacterium (bug) which is carried in the vagina and rectum of 2 - 4 in 10 women (20 – 40%) in the UK. GBS is not a sexually transmitted disease and most women carrying GBS will have no symptoms. Carrying GBS is not harmful to you, but it can affect your baby around the time of birth. GBS can occasionally cause serious infection in newborn babies and, very rarely, during pregnancy and before labour.

Many babies come into contact with GBS during labour or around birth. The vast majority of these babies will not become ill. However, if you carry GBS, there is a small chance that your baby will develop GBS infection and become seriously ill, or even die.

Infection is more likely to happen if: 

  • your baby is born preterm (before 37 completed weeks of pregnancy) – the earlier your baby is born, the greater the risk
  • you have previously had a baby affected by GBS infection
  • you have had a high temperature or other signs of infection during labour
  • you have had any positive urine or swab test for GBS in this pregnancy
  • your waters have broken more than 24 hours before your baby is born.

If you have had a GBS-positive swab or urine test in this pregnancy you will be offered antibiotics through a drip in labour to reduce the chance of infection. You will also be offered antibiotics if you have previously had a baby who was diagnosed with GBS infection.

If you have had GBS previously, some hospitals offer a specific test (enriched culture medium) to see whether you are carrying GBS again. If this test is not available in your local hospital, you will be offered antibiotics in labour instead. Please ask your midwife for more information.

You should discuss your planned place of birth with your midwife during pregnancy to make sure that you can receive antibiotics as required in labour. If you choose to have antibiotics, it may not be possible to arrange this at home or in some midwifery led units. Please ask your midwife for more information.

Further information is available here about GBS.

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