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Group B Streptococcus (GBS) in pregnancy and newborn babies

What is Group B Streptococcus (GBS)?

Group B Streptococcus (GBS) is a common bacterium which up to 1 in 4 women have in the vagina. Most women will be unaware of its presence and it is not necessary to take antibiotics to try to eradicate it.

Why does it 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. Whilst many babies are exposed to the bacteria without becoming unwell, 1 in 1750 newborn babies may develop a GBS infection. In a unit the size of Buckinghamshire Healthcare NHS Trust, this means 3 babies a year.

Screening in pregnancy

At Buckinghamshire Healthcare NHS Trust pregnant mothers are not routinely tested for the GBS infection. This is because many women are likely to have a different result by the time they give birth.

If a mother wants to be tested for the GBS infection, further information can be found on the GBS Support website.

Treatment during labour

During labour you will be given intravenous antibiotics (penicillin or an alternative) via a drip over a period of approximately 20 minutes if:

  • a vaginal swab or urine sample has shown the presence of GBS at some point during pregnancy
  • you have had a baby previously infected with GBS
  • your waters have been broken for more than 18 hours during labour
  • you develop a high fever during labour

Most GBS infections in newborn babies can be prevented by giving you antibiotics into a vein in labour. The first dose should be given at least 4 hours before the birth of your baby.

Assessment and treatment of the baby at risk of infection

Babies born after 37 weeks:
If the antibiotics were given 4 hours or more before delivery:

  • your baby will not need any extra checks

If the antibiotics were not given or were given less than 4 hours before the birth:

  • your baby will be assessed for signs of infection by a Paediatrician (baby doctor) at birth
  • your baby will have his or her observations checked regularly for 12 hours in total
  • if there are concerns about infection, the Paediatrician will speak to you about blood tests, intravenous antibiotics and any further tests that may be required
  • Paediatricians will recommend your baby is given intravenous antibiotics for up to 72 hours until the results of the blood tests are available. These will stop if no infection is found. If GBS is present, the antibiotics will continue for at least 5 days and in some cases up to 10 days.
  • information about how to check your baby for signs of GBS infection are on page 4.

Babies born before 37 weeks:

  • Paediatricians recommend your baby receives intravenous antibiotics until culture results are available, which may be up to 72 hours. If GBS is present, the antibiotics will continue for at least 5 days and in some cases up to 10 days.
  • side effects from short courses of antibiotics to newborn babies are very rare and the drug level is closely monitored

you may need to stay in the hospital with your baby after the birth, a little longer than you had planned—up to 5 days, or more, if your baby needs a full course of antibiotics. Usually you will both be on the postnatal ward. If your baby is unwell, he or she may need to be on the neonatal unit.

What to look for in your baby when you have returned home from hospital

At least 60% of GBS infections in babies are apparent at birth; around 90% are apparent within baby’s first 12 hours of life, with most GBS infections being detected and treated before you and your baby go home. However, a small number (10%) of affected babies still develop GBS after going home.

Signs of GBS infection are:

  • fever
  • poor feeding and/or vomiting
  • impaired consciousness—abnormally drowsy or withdrawn
  • shrill or moaning cry or whimpering
  • dislike of being handled, fretful
  • tense or bulging fontanelle (soft spot on the head)
  • involuntary body stiffening or jerking movements
  • floppy body
  • blank, staring or trance-like expression
  • altered breathing pattern/grunting
  • pale and/or blotchy skin

If your baby shows any of these signs, call your GP, Community Midwife or Health Visitor immediately. If you feel your baby is too unwell to wait for the arrival of one of the above, go straight to your nearest Accident and Emergency/ Casualty Department.

Useful Contact Numbers

If you require translation of this leaflet, please contact either:

  • Antenatal Clinic, Wycombe Hospital 01494 425575
  • Antenatal Clinic, Stoke Mandeville 01296 316227
  • Labour Ward, Stoke Mandeville 01296 316103

Or you can access the leaflet in 14 different languages via the Group B Strep website.

If you want to ask anything else related to your treatment please speak to the Antenatal Clinic or Labour Ward.


Royal College of Obstetricians & Gynaecologists. Prevention of early onset neonatal Group b Streptococcal disease. Guideline No. 36. September 2017.