Group B Streptococcus during pregnancy and birth

This information leaflet has been produced by Gateshead Health NHS Foundation Trust Maternity Unit to provide information to pregnant women who have GBS during pregnancy and for those who may be worried about GBS.

What is GBS?

Group B streptococcus (GBS) is part of the streptococcus family. It is a common bacterium (not a virus) which, like several others, normally lives in your body, including in the vagina and rectum. GBS usually causes no harm. However, if GBS is passed on from the mother to her baby around the time of the birth this can occasionally cause serious illness for the newborn baby.

What could it mean for my baby?

Approximately 1 in 4 pregnant women in the UK carry GBS in their vagina. Many babies therefore come into contact with GBS during labour or during birth, and GBS will colonise some of them. The vast majority of babies are not harmed by contact with GBS at birth.

A small number of babies, however, develop GBS infection and may become seriously ill.

Most babies who are infected show symptoms within 12 hours of birth. They may be floppy and unresponsive and may not feed well. Other symptoms may include grunting, high or low temperature, fast or slow heart rates, fast or slow breathing rates, irritability, low blood pressure and low blood sugar.

Out of every 2000 newborn babies in the UK and Ireland, only one is diagnosed with GBS infection; this means that about 340 babies each year are diagnosed with early onset neonatal GBS. Around one baby dies out of every ten who are diagnosed.

Although it is rare, GBS is the most common cause of life-threatening infection in babies during the first week after birth.

For a few babies who become ill but who have already had antibiotics, the doctors may suspect the illness is due to GBS infection although it is not possible to confirm this diagnosis (as the antibiotics will have already killed the bacterium). If there seems to be a higher risk of your baby being infected with GBS or if you have had a previous baby with GBS infection, you should be offered antibiotics during labour to reduce the chances of your baby developing the infection. Babies who show signs of GBS infection need to be treated with antibiotics to get well.

It is safe to breastfeed your new baby. Breastfeeding has not been demonstrated to increase the risk of GBS infection, and it protects against many other infections.

Are there tests for GBS?

GBS may sometimes be detected during pregnancy in the course of tests for other infections by taking a sample by swab (similar to a cotton bud) from your vagina and/or rectum.

As GBS can cause urine infection in pregnant women, GBS infection may also be detected by taking a mid-stream urine sample (MSU), which is then sent to a laboratory for analysis. Urine infection caused by GBS should be treated with antibiotics.

At the Queen Elizabeth Hospital, we take vaginal swabs when there is a history of:

  • Suspected vaginal infection with discharge
  • If your waters break

We will also send a specimen of urine to the laboratory:

  • When you first book with the midwife
  • If a urine infection is suspected at any time during your pregnancy

If there is a concern that a baby has GBS infection after birth, you will be offered treatment for your baby and testing to confirm that GBS is the cause of the infection. This testing will involve taking a sample of blood or a sample of fluid from the spinal cord. 

Routine testing for GBS is not necessary.

Why is there no national screening programme for GBS?

You will not be offered a test routinely for GBS during pregnancy as there is no national screening programme for this in the UK. There is conflicting evidence, and differing views, about whether a national screening programme would be effective.

Research is being carried out to provide a clearer picture.

The Royal College of Obstetricians and Gynaecologists (RCOG) guideline Prevention of early onset neonatal Group B streptococcal disease has carefully considered the benefits and harms of screening for GBS during pregnancy. It agreed that there is still no clear evidence to show that screening all pregnant women in the UK would be beneficial overall. 

One of the potential harms of screening for GBS during pregnancy is that large numbers of women would be given antibiotics during labour. 

The possible risks of this are:

  • death or serious injury to a very few women from an allergic reaction (anaphylaxis) to the antibiotics
  • strains of bacteria becoming resistant to antibiotics

What can help reduce the risk of GBS?

In some circumstances antibiotics can help to reduce the risk of a baby developing GBS and so you may be offered antibiotics during labour if:

  • GBS has been found in your urine in your current pregnancy
  • GBS has been found on swabs from your vagina and/or rectum which have been taken for another reason
  • you have previously had a baby with GBS infection
  • you are at higher risk of passing on GBS to your baby

This may be because:

  • you have a high temperature during labour
  • you go into labour prematurely (prior to 37 completed weeks of pregnancy)
  • you give birth more than 18 hours after your waters have broken

Depending upon your particular circumstance, your healthcare professional will discuss the option of antibiotic treatment during labour.

Penicillin is normally given; if you are allergic to penicillin, you should be offered an appropriate alternative. If your doctor thinks you may have an infection but is not sure of the cause, you should be offered antibiotics that will treat a wide range of infections including GBS.

When antibiotics are not necessary

If you carry GBS in your vagina, you should not need antibiotic treatment:

  • if GBS was detected in your vagina in a previous pregnancy and the baby was not affected

during pregnancy, unless you have a symptomatic infection (for example, a urine infection) though you may require antibiotics in labour

  • if you have a planned caesarean section before you go into labour and before your waters break.

The reason why antibiotics are not usually needed in these situations is that the risk of your baby becoming infected with GBS is so low and because antibiotics do not reduce your chances of carrying GBS at the time of the birth.

What will my treatment involve?

If you need antibiotics during your labour, it is best if you can start them as soon as possible after your labour starts. This will be given through a vein (intravenously). You should be offered further doses as necessary until the birth.

If you need intravenous antibiotics, it may not be possible to give birth at home. This may be a factor in your decision on where you will give birth.

If you need antibiotics during labour there may be concern about the risk of infection for your baby if for some reason you were not able to receive them, or if you delivered very soon after receiving them. The options of monitoring the health of your baby, or of treating him or her with penicillin, should be discussed between you and the medical staff taking account of the potential risks and benefits of each approach.

What treatment is available for my baby?

Babies with any signs of GBS infection, for example, if the newborn baby is floppy and unresponsive and does not feed well, should be treated with antibiotics as soon as possible. If you have had a previous baby with GBS, your healthcare team should either monitor the health of your newborn baby closely for at least 12 hours after birth, or treat him or her with penicillin until blood tests confirm whether or not GBS is present.

Babies who show no signs of GBS and who are well do not routinely receive antibiotics or tests for GBS.

What might happen without treatment?

If your doctor recommends that you take antibiotics because of risk factors such as a high temperature in labour, and you choose not to, your baby may be at higher risk of GBS infection.

If your baby has GBS infection and is not treated with antibiotics, he or she is likely to become seriously ill.

Is there anything else I should know?

No screening test is entirely accurate. A screening test for GBS carriage could give a falsely negative result. In other words, a woman would be given a negative result when in fact she carried GBS in her vagina.

No treatment can be guaranteed to work all the time for everyone. Even with antibiotic treatment in labour, some babies still develop GBS infection.

You have the right to be fully informed about your health care and to make decisions about it. Your healthcare team should respect these decisions.

How can I find out more information?

Please discuss any queries or concerns with your midwife or consultant during your appointment; alternatively if you need any more information please do not hesitate to contact the Maternity Pregnancy Assessment Unit to speak to a midwife.

Pregnancy Assessment Unit  – 0191 445 2764

(24 hours 7days) 0191 445 3678              

Other information

National Childbirth Trust

Group B Strep Support 


RCOG (2013) Preventing group B streptococcus (GBS) infection in newborn babies. Royal College of Obstetricians and Gynaecologists

Data Protection

Any personal information is kept confidential. There may be occasions where your information needs to be shared with other care professionals to ensure you receive the best care possible.

In order to assist us improve the services available your information may be used for clinical audit, research, teaching and anonymised for National NHS Reviews.  Further information is available in the leaflet Disclosure of Confidential Information IL137, via Gateshead Health NHS Foundation Trust website or the PALS Service