Group B streptococcal (GBS) colonisation

Warning
  • The likelihood of maternal GBS carriage in pregnancy is 50%.
  • GBS can be passed from mother to baby. When this happens it can occasionally cause severe illness in the newborn (this is known as neonatal GBS).
  • Only 1 in every 2000 newborn babies born in the UK and Ireland is diagnosed with neonatal GBS.
  • Women in whom GBS has been found in the urine or swabs from the vagina (or rectum) taken for other reasons are likely to be offered antibiotics during labour. It is important that the pregnant women and their obstetric team are made aware of the presence of colonisation.
  • Women with GBS in the vagina do not need antibiotics in pregnancy prior to labour unless they have a symptomatic infection (for example a urine infection).
  • Women with GBS urinary tract infection during pregnancy should receive antibiotics at the time of diagnosis (on discussion with the women’s obstetric team) as well as during labour.
  • Antenatal prophylaxis for vaginal/rectal colonisation detected incidentally earlier in a pregnancy does not reduce the likelihood of colonisation at the time of delivery so is not recommended.
  • There is no national screening programme for GBS in the UK as there is no clear evidence to show that screening all pregnant women in the UK would be beneficial overall.
  • Vaginal swabs should not be taken in pregnancy unless there is a clinical indication to do so.
  • The RCOG have written a patient information leaflet for women who are expecting a baby or planning to become pregnant about Group B streptococcus infection which is available here.

Editorial Information

Last reviewed: 31/01/2024

Next review date: 31/01/2024

Author(s): West of Scotland Managed Clinical Network for Sexual Health Clinical Guidelines Group .

Version: 6.1

Approved By: West of Scotland Managed Clinical Network in Sexual Health