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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. It’s not necessary to take antibiotics to try to eradicate it.

Why does it matter?

Although GBS doesn’t cause any problems for the woman, it’s 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 1,750 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 you want to be tested for the GBS infection, visit the GBS Support website for more information.

Treatment during labour

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

  • a vaginal swab or urine sample shows 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 24 hours
  • you develop a high fever during labour.

If you’re a known carrier of GBS during your pregnancy, call us as soon as your contractions start or if you suspect that your waters have broken. We can then assess the most appropriate plan for your admission.

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

For babies born after 37 weeks

If you have the antibiotics 4 hours or more before delivery, your baby will not need any extra checks.

If the antibiotics weren’t 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
  • have his or her observations checked regularly for 12 hours in total.

The paediatrician will speak to you about blood tests, intravenous antibiotics and any further tests if there are concerns about infection.

Paediatricians will recommend your baby has 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.

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 we closely monitor the drug level.

You may need to stay in hospital with your baby after the birth a little longer than planned. This could be up to 5 days or more if your baby needs a full course of antibiotics.

Usually you’ll both be on the postnatal ward. If your baby is unwell, he or she may need to be in 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 evident at birth. Around 90% are evident within baby’s first 12 hours of life, with most GBS infections 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 include:

  • a 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, call 999.

If you need any help

Contact us on the numbers below if you need:

to ask anything related to your treatement
a translation of this information.

You can also access the information in 14 different languages via the Group B Strep website.

Reducing associated healthcare infections

Find out how you can help to reduce healthcare associated infections when visiting hospital


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

Contact us

Antenatal Clinic, Wycombe Hospital
Antenatal Clinic, Stoke Mandeville Hospital
Labour Ward, Stoke Mandeville Hospital
Antenatal Clinic, Wycombe Hospital

01494 425575

Antenatal Clinic, Stoke Mandeville Hospital

01296 316227

Labour Ward, Stoke Mandeville Hospital

01296 316103