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Group B Streptococcus: the most common life-threatening infection for new-born babies, but have you even heard of it?

Posted: 12/07/2021

Group B Streptococcus, also known as GBS, is a naturally occurring bacteria in the human gut that does not pose any risk of harm for the vast majority of adults. It often travels from the gut into the rectum and can also travel from the rectum to the vagina. GBS is relatively common and affects between 20% and 40% of women.

GBS can lead to infection (GBS disease) in adults but this is very rare. Far more concerning is that GBS can be passed from mothers to new-born babies during delivery. If a baby is infected with GBS, it can lead to life-threatening illnesses including sepsis, pneumonia and meningitis.  

If a mother is known to be a GBS carrier or is at high risk, antibiotics can be prescribed during labour to reduce the risk of her baby developing early-onset GBS infection. With antibiotic treatment, the risk of GBS infection within the first week of life reduces from around one in 400 to one in 4,000.[1] 

Approximately one in every 1,750 babies born in the UK and Ireland will develop early-onset GBS infection in the first six days of life and one in 2700 will develop late-onset infection between one week and three months of age. Of the early onset infections, 5% will die and a further 7% will develop disabilities. Of the late onset infections, nearly 8% of babies will die and, of those who survive, more than 12% will have a long-term disability. [2] 

In 2017, researchers for the Clinical Infectious Diseases journal found that worldwide GBS caused 409,000 cases of GBS disease in new-borns every year, including 147,000 infant deaths and stillbirths.[3]

Worryingly, Group B Strep Support (GBSS)  – Working to stop Group B Strep infection in babies has reported that England’s rate of GBS infection in babies rose by 77% between 1996 and 2020.[4] Despite increasing numbers of GBS infections and the potentially serious consequences for babies, GBS is still not routinely screened for in pregnant women in the UK. 

Since 2017, the Royal College of Obstetricians and Gynaecologists (RCOG) has recommended testing some pregnant women, including those who have had GBS detected in a previous pregnancy. This means that most mothers are not tested and GBS is usually found by chance when performing routine urine tests or vaginal or rectal swabs. 

An Enriched Culture Medium (ECM) test has been specifically designed to identify GBS and is very accurate when used. Unfortunately, a high vaginal swab (HVS) test is sometimes used to detect infections and, according to research published in the Journal of Obstetrics and Gynaecology, HVS may only be 50% accurate for GBS[5]. This means that, when this test is used, it could be failing to identify up to half of pregnant GBS carriers. At present, the NHS only offers GBS testing to ‘high risk’ women but research shows that it is difficult to accurately identify which women and babies are most at risk.  

Although any baby can develop early-onset GBS infection, it is more likely to develop in the following circumstances:  

  • The baby is pre-term
  • The mother has had a previous baby with GBS infection
  • The mother has a high temperature in labour
  • The mother had a GBS positive urine or swab test in pregnancy
  • The mother’s membranes ruptured more than 24 hours before delivery.

Late-onset GBS is less common but usually effects babies who are preterm and/or whose mothers had a positive GBS test during pregnancy.   

For expectant mothers who are concerned, ECM testing is available privately and advice about getting tested can be found on the Group B Strep Support website at GBS bacteria can come and go so it is important to get tested at the right time. If a mother screens positive for GBS at 35 weeks, they may no longer be GBS-positive at delivery.

Conversely, it is possible that GBS colonises the vagina between screening and delivery. It is therefore recommended that testing takes place at 35-37 weeks gestation (or 3-5 weeks prior to anticipated delivery) to ensure that the result is as accurate as possible at the time of delivery.  

Treatment for women who test positive for GBS

For women who test positive for GBS during their pregnancy or who have had a previous baby affected by GBS disease, the RCOG recommends intrapartum antibiotic prophylaxis (IAP). Antibiotic treatment is given during labour as any treatment provided before labour does not reduce the chance of a baby developing GBS infection. If GBS is detected on a urine test, the woman should receive antibiotics for the urinary tract infection at the time of diagnosis and should also be offered antibiotics through a drip during labour.

The RCOG recommends immediate IAP and induction of labour as soon as possible for women with a rupture of membranes who are known to be a GBS carrier. IAP is also recommended for all women in pre-term labour, irrespective of GBS status. Antibiotics are a very effective method of preventing early-onset GBS infection and, when administered to mothers during labour, they significantly reduce the risk to their babies. 

GBS infection often develops very quickly, within an hour or two of birth, but can also occur up to three months after birth (late onset). Unfortunately, there are no known methods of preventing late-onset GBS infection so it is important that parents are aware of the symptoms and seek medical assistance if they are concerned.

GBS symptoms

The symptoms of GBS infection in babies include inconsolable crying, listlessness, floppiness, difficulty feeding, abnormal temperature, rapid breathing and grunting, and a change in skin colour. For babies with clinical signs of GBS infection, urgent care is imperative and intravenous antibiotic treatment should be commenced within one hour of diagnosis.

Should routine GBS screening be introduced?

With GBS infection rates rising in the UK, it is important to consider how the number of babies suffering from this infection can be reduced and whether the NHS should offer routine GBS screening. Although former Prime Minister David Cameron campaigned for universal NHS screening in April 2004[6], this has still not happened despite the fact that the NHS routinely screens pregnancies for much rarer conditions such as Spina Bifida, HIV, syphilis, and Hepatitis B.

One argument against universal screening is the lack of studies to show that tests are effective or that widespread testing reduces negative outcomes. However, GBSSs point to the evidence from countries where testing is now routine and rates of GBS in those countries fell significantly -  by over 80% in the US, 86% in Spain, 82% in Australia and 71% in France.[7]

The National Institute for Health Research (NIHR) is currently investigating the effectiveness of screening and acknowledges that the current UK policy is not very effective. Previous research in the UK has found that 65% of babies who develop the infection have mothers who do not have risk factors for carrying the bacteria, whereas 70% of women who have risk factors do not actually harbour the bacteria. 

The trial will compare the current treatment with using a lab culture test to check all women at 35 weeks of pregnancy and  with doing a ‘bedside test’ at the start of labour. It is understood that the results of this trial will not be published until 2023 but it is an important trial that will inform future pregnancy screening policy in the UK.[8]

Another argument against routine testing is the expense of testing and antibiotics. However, GBBS states: “Since 2003, the UK has used ‘risk factors’ to guess which pregnant women might be at risk. Risk factors are poor at predicting which babies will develop group B Strep infection – the number of babies infected is growing, we need to stop guessing and start testing. The group B Strep-specific ECM test costs the NHS £11 each and the antibiotics used in labour (usually Penicillin) cost the NHS pennies.”[9]

There is also the concern about the overuse of antibiotics and allergic reactions. GBS-positive patients are usually treated with benzylpenicillin alone, not broad-spectrum antibiotics and women with a known penicillin allergy can be offered alternative antibiotic treatment. 

Sarah Hibberd, a clinical negligence solicitor at Penningtons Manches Cooper who specialises in maternal care and birth injury claims, says: “Raising awareness about GBS is so important as it relatively common but the vast majority of parents haven’t even heard of it. The RCOG advises that all pregnant women should be given an information leaflet about GBS but expectant parents are given many leaflets and are very rarely provided with any further information or advice. 

“For a condition which can cause devastating consequences but is easily treatable with antibiotics, GBS should be discussed with all expectant parents so they can understand the risks and make an informed decision about whether they wish to undergo testing, either through the NHS, if available, or privately. 

“As an expectant parent, it is your natural instinct to protect your baby from any unnecessary risk and if you are able to access ECM testing, at the right time in your pregnancy, you will be able to find out whether you are a carrier of GBS.  The cost of a private ECM is around £35 and knowing your GBS status can provide much needed peace of mind. 

“Every parent and carer should be made aware of the signs and symptoms of GBS infection so they can be vigilant in the hours, weeks and months following birth. Knowledge of the symptoms will help ensure that any concerning symptoms are promptly and properly investigated and treated. 

“Thankfully, with timely and appropriate care, most babies will survive GBS infection.  However, failures in care can also contribute to the number of deaths and have devastating consequences for families.” 

If you are concerned about the care that has been provided to you or a loved one during pregnancy, labour or in the neonatal period and would like to speak to someone, please contact our specialist team who are experienced in pregnancy and birth injury claims and can advise on the available options.  



[3] Seale et al, 2017, Available at:

[4] GBSS, 2 June 2021, Available at:

[5] Guardian,



[8] NIHR News, 15 May 2019, Available at:



This article has been co-written with Dominik Young, a trainee solicitor in the clinical negligence team.

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