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Group B Streptococcus (GBS)

This article looks at Group B streptococcus (GBS). Read more about the prevention of GBS and treatment of early-onset infection in newborn babies.

This article covers:

What is GBS?
Will GBS in pregnancy affect my baby?
What are the signs and symptoms of GBS in babies?
What treatment options are available for babies infected with GBSS?
What can be done to reduce the risk of GBS infection in babies?
When are antibiotics not necessary?
Are there any risks with antibiotics for GBS?
Will I be screened for GBS?
Why are all women not tested for GBS during pregnancy in the UK?

What if I want to be screened?
Do I have to have the screening or treatment if it is offered?
Will the treatment affect how and where I give birth?
Further information

What is GBS?

Group B Streptococcus (GBS) is a common bacterium found in the vagina and bowel of about 2 in 10 women in the UK. This is described as being a GBS carrier (or as being ‘colonised’ with GBS). Being a carrier is not harmful for you, and GBS is not sexually transmitted.

Will GBS in pregnancy affect my baby?

Most women who are carriers give birth with no ill effect to their baby and without ever knowing that they have GBS. Fortunately, if GBS is passed from mother to baby around the time of birth, the overwhelming majority don’t actually develop an infection. However, there is a small chance that your baby will develop an infection and become ill.

Infection is more likely to occur if:

  • Your baby is born prematurely.
  • You previously had a baby who developed GBS infection.
  • You have a high temperature during labour.
  • More than 18 hours pass between your waters breaking and your baby being born.

Around 1 in every 2,000 babies in the UK and Ireland are diagnosed with GBS infection. If a baby develops GBS infection less than seven days after birth, it’s known as early-onset GBS infection, and most often this is due to GBS passing from mum to baby around the time of birth. Late-onset infection is more commonly due to infection from other sources.

Most babies who are infected can be treated successfully with antibiotics and make a full recovery. However, some babies develop life-threatening complications, such as pneumonia, septicaemia or meningitis. One in 10 babies infected with GBS will die from the infection. Another 1 in 5 babies will develop longer-term problems with their development.

What are the signs and symptoms of GBS infection in babies?

Most babies who become infected develop symptoms within 12 hours of birth.  Symptoms include:

  • Being floppy and unresponsive
  • Not feeding well
  • Grunting
  • High or low temperature
  • Fast or slow heart rates
  • Fast or slow breathing rates
  • Irritability

If your baby is at increased risk of GBS infection, they will be monitored for signs of infection.

What treatment options are available for babies infected with GBS?

If your newborn baby shows signs of an infection, tests will be done to see whether GBS is the cause. This may involve taking a sample of your baby’s blood, or a sample of fluid from around your baby’s spinal cord (a lumbar puncture). It is recommended that babies with signs of GBS infection should be treated with antibiotics as soon as possible. Treatment is then stopped if there is no sign of GBS after at least 24 hours, or if tests are negative.

What can be done to reduce the risk of GBS infection in babies?

Antibiotics given intravenously during labour can help to reduce the risk of a baby developing GBS. The National Institute of Health and Social Care Excellence (NICE) has issued guidance on the prevention and treatment of early-onset infections in newborn babies. This guidance recommends the use of antibiotics in the circumstances set out below, based on the balance of risks and benefits to mum and baby. The NICE guidance says that:

  • IV antibiotics during labour should be offered to women when GBS has been identified incidentally (e.g. when testing for the cause of a urinary infection) in their vagina, rectum or urine in this pregnancy, and to women who have previously had a baby with a neonatal GBS infection.
  • IV antibiotics should be considered for two groups of women in pre-term labour (i.e. before 37 weeks): those whose waters broke before the labour started and those whose waters have been broken for more than 18 hours before birth.
  • IV antibiotics should be prescribed if there is evidence of infection in the women, such as raised temperature.

New RCOG guidelines now recommend all women who go into preterm labour, regardless of whether their waters have broken, receive intravenous antibiotics during labour to prevent onset of the GBS infection.

The NICE guidance also supports the principle of families being able to make informed choices about aspects of care for mothers and babies. If you need more information or want a particular form of care, do talk to your midwife or doctor.

When are antibiotics not necessary?

Oral antibiotics taken before labour do not reduce the chances of carrying GBS at the time of birth.

NICE guidance about the care of healthy women and their babies during childbirth also states that antibiotics should not be given to either the woman or the baby if there are no signs of infection in the woman, even if the waters have been broken for over 24 hours. In those circumstances they recommend induction of labour approximately 24 hours after rupture of the membranes.

Are there any risks with antibiotics for GBS?

As with any drugs, antibiotics may present risks of their own. There are risks of having an allergic reaction to antibiotics (a one in 10 risk of a mild reaction to penicillin, and a one in 10,000 risk of a severe reaction). Some women may experience temporary side effects such as diarrhoea or nausea. However, for most women antibiotics are safe.

It is thought that babies exposed to antibiotics very early in their lives may have a higher than usual risk of asthma and/or other allergies later in life.

Will I be screened for GBS?

There is no routine UK national screening programme to find out whether pregnant women carry GBS. Instead, NICE guidelines recommend that antibiotics are offered to women who have particular risk factors or circumstances. 

Why are all women not tested for GBS during pregnancy in the UK?

The National Institute of Health and Social Care Excellence (NICE) recommends that GBS screening is not offered to all women, because evidence of its clinical and cost effectiveness remains uncertain. Similarly, the National Screening Committee concluded that there is not clear evidence that screening would be beneficial overall. This is an ongoing area of debate and the national screening recommendations are due to be reviewed in 2015/16. NICE has set three objectives:

  • Prioritise the treatment of sick babies.
  • Minimise the impact of managing infections on healthy women and babies. (In other words, try to ensure that the approach used for identifying and treating infections does not jeopardise the health and wellbeing of healthy women and babies.) 
  • Use antibiotics wisely to avoid the development of resistance to antibiotics.

The reasons for not offering routine testing include:

  1. Most babies born to women who carry the bacterium do not become infected.
  2. It is not clear whether screening all women during pregnancy to see if they carry GBS would do more good than harm. Identifying women who are GBS carriers in order to treat them all with antibiotics during labour would result in many thousands of women and babies being treated in order to prevent a very small number of serious infections.
  3. There are important concerns about using antibiotics on this scale. Around 150,000 women each year would receive the drugs during labour by an intravenous (IV) route, i.e. through a tube into a vein. Concerns include the possible effect on the newborn babies’ normal gut flora (healthy bacteria); the risk of allergic reaction among the women receiving the drug; growing resistance to antibiotics in the whole population; and the potential negative impact on care during labour and outcomes for mother and baby.
  4. In countries where a screening programme has been introduced, it is carried out at around 36-37 weeks of pregnancy. Women whose babies are born pre-term, i.e. before this stage, would therefore not normally have been offered the option of screening.

What if I want to be tested for GBS?

Contrary to national guidelines, some maternity units do offer GBS testing for women with particular risk factors or who request testing (RCOG 2016). If you would like to be tested, ask your midwife or doctor about local policies and what options are available to you. Tests are also available privately – you can find a list of organisations which follow methodology described by Public Health England’s UK Standards for Microbiology Investigations on the Group B Strep Support website.

Do I have to have the screening or treatment if it is offered?

The decision as to whether or not to have the screening or to have antibiotics during labour is yours. Some women weigh up the risks and benefits and decide not to. Other women are keen to be tested or to have intravenous antibiotics during labour as a precaution. It can be difficult to make sense of the information and the options. You may need support and a chance to discuss what you feel is right for you and your baby. Do talk to a midwife or doctor if you have questions.

Will the treatment affect how and where I give birth?

Often, women are advised to give birth in hospital if they are planning to have IV antibiotics. However, a recent audit showed that many midwifery-led units do accept women in labour who are GBS carriers and have IV antibiotics available. You will need to discuss your options with your midwife or doctor. For example, it may be useful to know what your options are for where you give birth, which units have GBS-specific antibiotics available and what the transfer arrangements would be, should you need to transfer to hospital from home or a midwifery-led unit.

There is a small risk of developing an allergic reaction to antibiotics and it is easier to respond to an adverse reaction in hospital. However, some community maternity services have been able to arrange medical cover for women carrying GBS who wish to give birth at home or in a midwifery-led unit.

Connection to an IV line throughout labour tends to reduce mobility, which may slow the progress of your labour. However, women receiving IV antibiotics in labour do not need to be connected to a drip throughout the whole of labour. Usually a cannula is inserted into a vein in the back of the hand and remains there until after the baby is born. The antibiotics can then be given through this cannula at the required intervals, either by slow injection (over several minutes) or by drip (over half an hour or so). When the antibiotics have gone through, the cannula can be detached from the drip and the woman is then free to move around as she wishes. 

It is more difficult to use water during labour if you have IV antibiotics. However, if you feel strongly that you would like to use a birth pool and you are planning IV antibiotics, talk to your midwife about whether it can be arranged. It has been successfully arranged in some cases.

Page last updated: September 2017

Further information

NCT's helpline offers practical and emotional support in all areas of pregnancy, birth and early parenthood: 0300 330 0700. We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.

The Royal College of Obstetricians and Gynaecologists and NHS Choices have information on their screening policy for Group B Streptococcus.

Group B Strep Support offers information and support to families affected by this condition. They have a useful patient information leaflet about GBS in pregnancy and newborn babies.