CUH NHS 75th birthday logo

Group B Streptococcus (GBS) - Your pregnancy and your baby

Patient information A-Z

What is (GBS)?

Group B Streptococcus (GBS) is a type of bacteria that is found in the intestine of about a third of all adults and in the vagina and rectum of 2 to 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. Antibiotics in pregnancy cannot always eliminate it although when detected in a urine sample, antibiotics are advised at the time of detection in pregnancy.

What should I know about GBS?

GBS is the most common cause of early onset bacterial infection in babies (infection that arises within 72 hours of birth). Around 1 in every 1750 newborn babies in the UK and Ireland is diagnosed with early onset GBS infection. The infections that GBS most commonly causes in newborn babies are sepsis (infection of the blood), pneumonia (infection in the lungs), and meningitis (infection of the fluid and lining around the brain). Although GBS infection can make your baby very unwell, with prompt treatment most babies will recover fully. However, of the babies who develop early-onset GBS infection, 1 in 19 (5.2%) will die and, of the survivors, 1 in 14 (7.4%) will have a long-term disability.

On average in the UK, every month

  • 43 babies develop early-onset GBS infection
  • 38 babies make a full recovery
  • 3 babies survive with long-term physical or mental disabilities
  • 2 babies die from their early-onset GBS infection

In the UK, the NHS does not routinely offer all pregnant women screening for GBS.

The risk of GBS being passed from a mother to her baby is highest during labour or at the time of birth but the vast majority of babies will be unaffected. Why a small number of babies do become infected is uncertain. What is clear is that most, but not all, GBS infections in newborn babies can be prevented. This is achieved by giving women who are identified as being at risk of passing the infection to their baby intravenous (IV) antibiotics (antibiotics given into a vein) during labour or from when the waters break until the baby is born.

Which babies are most at risk of infection including GBS after birth?

There is an increased risk of neonatal GBS infection in the following circumstances:

  • where there is prolonged rupture of membranes (more than 18 hours before delivery)
  • where GBS has been found in the vagina, cervix, rectum or urine during the current pregnancy
  • where a previous baby was affected by GBS disease
  • where labour starts prematurely ie before 37 weeks
  • where there is a raised temperature (38oC or higher) during labour or if the mother requires IV antibiotics for a bacterial infection in labour or within the first 24 hours after giving birth
  • where there is other evidence of infection of the amniotic fluid
  • when there are twins and infection is suspected in one of the babies

Giving women IV antibiotics at least two hours prior to delivery has been proven to be effective in preventing most GBS infections in newborn babies.

However, there are some risks associated with receiving antibiotics such as allergic reaction to the antibiotics, strains of bacteria becoming resistant to antibiotics and additionally, it is thought that babies exposed to antibiotics very early in life may have a higher than normal risk of asthma and/or other allergies later in life. These risks have to be balanced with the risk of potentially having an affected baby and you may wish to discuss this further with the healthcare professionals caring for you.

Late onset disease

The warning signs of the late onset disease are the same but in many cases they develop over a longer period (days).

The risk of a baby of developing GBS infection decreases with age. GBS infection in babies is rare after one month of age and virtually unknown after three months.

GBS or other bacteria may be passed by physical contact, so everyone (including parents), whether they carry GBS or not, should wash their hands and carefully dry them before handling any baby for the first three months of life.

If you have any questions regarding GBS prior to, or after the birth of your baby, please discuss them with your midwife, obstetrician or your GP.

If you have a particular concern about GBS and require a more detailed discussion, please arrange an appointment to speak to one of the neonatal consultants on: 01223 586629


If you are found to have the GBS bacterium within 72 hours of your baby’s birth, your midwife/GP should ask whether you have any concerns about your baby, and they will check for any other risk factors and signs of infection in the baby. If there are no symptoms, signs or risk factors in the baby, your health professional will reassure you and give you information about what to look out for.

Signs of GBS infection in a baby

GBS infection may become apparent in some babies shortly after birth and before discharge from hospital.

Early onset disease (typically occurs in the first 72 hours after birth)

Warning signs of infection in a baby include:

  • limp or floppy baby
  • rapid breathing or difficulty with breathing, particularly more than four hours after the birth
  • fever or low body temperature, or signs of shock
  • poor feeding, vomiting
  • pale or blue colour
  • jaundice within the first 24 hours of birth
  • shrill or moaning cry
  • whimpering
  • lethargy, irritability
  • abnormal movements, seizures or fits
  • unexplained bleeding, low blood sugars
  • small amounts of urine persisting beyond 24 hours
  • localised infections eg of the skin or eye

IV antibiotic therapy successfully treats most babies. Sadly, even with the best medical care, a small number of babies die each year from their infection (GBS septicaemia, pneumonia or meningitis). Some survivors may suffer long term problems.

A few babies may develop the infection after discharge from hospital.

If your baby shows any of the above signs of GBS infection, take your baby to your GP or the Emergency Department of your local hospital. Early diagnosis and treatment are vital and delay could be fatal.

How do I find out if I carry GBS?

You will not be offered a test specifically for GBS carriage routinely during your pregnancy as it is not currently recommended in the UK by either the UK National Screening Committee or the Royal College of Obstetricians. Current evidence does not support universal screening in view of the potential risks associated with large numbers of women receiving antibiotics during labour (see paragraph above). A ‘risk-based’ approach is recommended in the UK where women with certain risk factors are identified and assessed (e.g., preterm labour, pre-labour rupture of membranes, prolonged rupture of the membranes or fever during labour); in these circumstances additional tests are carried out and if found to be GBS positive IV antibiotics will be offered during labour.

GBS can also be an incidental finding if a vaginal swab or urine test is performed for other indications during pregnancy.

You may access private testing for GBS if you wish. The RCOG does not recommend this however, as a negative swab does not guarantee that you are not a carrier of GBS, and a positive result may result in unnecessary and potentially harmful interventions.

If you have been known as GBS positive in previous pregnancies, we now offer bacteriological testing between 35-37 weeks gestation. The offer of intravenous antibiotics in labour if still screening GBS positive is available.

Recommendations for the prevention of GBS infection in newborn babies:

  • If you have risk factors for GBS, you will be recommended to have IV antibiotics during labour until delivery.
  • For women in labour, the recommended antibiotic is Benzylpenicillin. If you are allergic to Penicillin, you will be given Cefotaxime or Vancomycin
  • IV antibiotics should be given at least two hours prior to delivery.
  • Management of the baby after birth will depend on which risk factors(s) apply to you and your baby, and whether your baby shows any signs of infection. Sometimes all that is required is a period of monitoring of your baby by a midwife for at least 12 hours and sometimes an infection screen (blood tests) will be advised together with observation and treatment of your baby. This decision will be made on an individual basis and discussed with you after the birth.
  • If you do not receive IV antibiotics in labour, either because labour is too rapid, or you choose not to have IV antibiotics, then an individualised plan will be made for your baby and discussed with you. The plan could include monitoring for 12 hours or more, or an infection screen, depending on which risk factor(s) apply to you and your baby.
  • If your waters break more than 18 hours before delivery and you are known to have GBS then an infection screen (blood tests) on your baby will be advised and that your baby should remain in hospital for at least 36 hours.
  • If an infection is strongly suspected, a sample of fluid from around the baby’s spinal cord may be taken (a lumbar puncture) to exclude meningitis. If this is confirmed, IV antibiotics will be recommended for your baby who will be admitted to a neonatal unit for close observation. In this situation, further information regarding your baby’s care will be given to you, including the likely duration of treatment.
  • If you are known to carry GBS and your waters break before labour, we will explain your options of either waiting for labour to start spontaneously or proceeding with induction of labour. Currently, there is a lack of evidence to guide our practice however; our current recommendation is to offer immediate induction of labour together with IV antibiotics.

What if I have been found to carry GBS and I am having a planned caesarean section?

In theory, having a caesarean section does not prevent transmission of GBS from you to your baby. However, the risk is believed to be extremely low in planned caesarean sections performed before labour has started and where the waters have not broken. If you have been found to carry GBS in your vagina, cervix or rectum and are having a planned caesarean section you will not require IV antibiotics. It is recommended that your baby is observed in hospital for a minimum of 12 hours after birth.

Future pregnancies

If your baby has been treated for a GBS infection, your healthcare team will advise you that any babies you have in the future will also be at increased risk of early onset neonatal bacterial infection. You should tell the maternity care team that a previous baby has had a GBS infection, and you will be advised to have antibiotics during labour. The healthcare team should also write to your GP about the small risk of the infection recurring in the baby, and also about the risk of GBS affecting future babies.

If you have had GBS in this pregnancy but the baby did not have an infection, this will not affect the birth if you become pregnant again.

Further information about GBS can be obtained from:

GBS Support Group

Web-site: Group B Strep Support

Tel/answer phone: 01444 416176 (Mon to Fri 09:00 to 15:30)


We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151