What is Group B streptococcus?

Group B streptococcus (GBS) (Group B Strep) bacteria is one of many bacteria that can be present in our bodies. It does not usually cause any harm. It is called carrying GBS or being colonised with GBS.

It is estimated that approx. 25% of pregnant women carry the GBS bacterium in the UK in their digestive system or vagina.

How can Group B Strep affect my baby?Strep B Test UK

One newborn baby a day develops a Group B Strep infection coming into contact with GBS during labour and birth. If Group B Strep is passed to a baby, they are at risk of developing a GBS infection.

Early onset GBS infection:

Around two thirds of GBS infection are early-onset and occur within the first week of a baby’s life. Most babies who become infected develop symptoms within 12 hours of birth.


Early onset usually presents as pneumonia, sepsis, or meningitis, and may display the following signs:

  • grunting, noisy breathing, moaning, seeming to be working hard to breathe when you look at their chest or tummy or not breathing at all
  • be very sleepy and/or unresponsive
  • be crying inconsolably
  • be unusually floppy
  • not feeding well or not keeping milk down
  • have a high or low temperature and/or their skin feels too hot or cold
  • have changes in their skin colour (including blotchy skin)
  • have an abnormally fast or slow heart rate or breathing rate
  • have low blood pressure*
  • have low blood sugar*

*Identified by tests done in hospital

Although the majority of early onset GBS infections do not lead to chronic damage and most newborn babies will recover from their GBS infection it can cause long-term problems such as cerebral palsy, deafness, blindness, and serious learning difficulties.

Strep B Test UK1 in 17 newborn babies with GBS infection will die and 1 in 14 babies who survive their GBS infection will be affected permanently.

Up to half of survivors with GBS meningitis will suffer from physical disability, brain damage, mild to moderate learning disability, deafness, blindness, and lung damage.

If you have previously had a baby with GBS or know that you are a carrier you should be offered antibiotics during labour and your maternity team will monitor the health of your newborn baby closely for at least 12 hours after birth and treat them with antibiotics where necessary.

Most babies who become infected can be treated successfully and will make a full recovery.

Early-onset GBS Infection is more likely if:The importance of testing for GBS

  • your baby is born before 37 weeks of pregnancy
  • you previously had a baby with a GBS infection
  • your baby is born more than 24 hours after your waters broke
  • you have a high temperature during labour
Pregnant women are not routinely screened for GBS in the UK, but it is sometimes detected when tests for other infections are carried out.

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