GBS – another acronym to add to your ever increasing pregnancy, birth and parenting lexicon. It stands for Group B Strep.
Group B Strep is a commonly occurring bacteria in the human microbiome which can mostly be found hanging out in our large intestine, rectum, vagina and urinary tract and in adults is mostly harmless. It can occasionally be the cause of Urinary Tract Infections (UTIs) and can very very rarely be the cause of serious newborn infections. All around the world about 18% of people carry GBS.
There are more resources and references at the end of this blog, but if you want to know more about Group B Strep and how you feel about testing availability – you can’t go wrong buying and reading this book by Dr Sara Wickham. [affiliate link]
Here’s a brief bit about the numbers to put the rest of this blog in to context
- About 1 in 1750 new born babies are diagnosed with early onset GBS infection – that’s 0.06% so 99.94% are not.
- The chance is higher if the baby is born before 37 weeks, and most babies who are seriously affected are born before the current suggested time for screening (35-37 weeks)
- Babies can come in to contact with GBS on their skin, nose and mouth as they travel down the birth canal during a vaginal birth. Most babies do not become sick even after this contact.
- If a birthing person who carries GBS is not treated with antibiotics during labour the chance of the baby also becoming a carrier is 50% (not the same as having early GBS disease) and the risk of early GBS disease is 1-2% (so 98-99% of babies born do not become sick)
- On the other hand if a GBS carrier is treated with antibiotics during labour the chance of the baby developing early GBS disease reduces by 80% so from 1-2% to 0.2 – 0.4%
- GBS is the most common proven cause of early-onset infection (accounting for 40% of all isolates in culture positive cases) in the UK. So 60% of early onset sepsis are not caused by GBS
- Early onset GBS infection – when the baby is less than 7 days old – is a serious risk to babies long term health and survival and usually requires a stay in NICU
Why is there a Study?
The primary research aim for the study is:
Does routine testing of women for GBS colonisation either in late pregnancy or during labour reduce the occurrence of early-onset neonatal sepsis, compared to the current risk factor based strategy?
GBS3 Trial, Protocol Document
The testing and treatment for GBS in pregnant people varies around the world.
The UK uses the Risk based approach – Which is to treat labouring people with antibiotics if they have one or more of these risk factors:
- GBS in the urine at any point in pregnancy,
- previously gave birth to an infant with early GBS infection,
- goes into labour at less than 37 weeks,
- has a fever during labour,
- or water has been broken for more than 18 hours”
But since the 1990’s the US have been operating a universal screening programme.
In the early 1990s, before the American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics (AAP) recommended universal screening for GBS and treating it with IV antibiotics during labor, there were 1.8 cases of early GBS disease per 1,000 live births (ACOG 2019). [0.18%]
After the newer recommendations went into action, rates of early GBS disease in the U.S. dropped drastically. In the most recent data set, … there are only 0.2 cases of early GBS disease per 1,000 live births (CDC, 2020). [0.02%]
In England, where the other risk factor approach is used to lower the risk of early GBS disease, the 2020 rate of early GBS disease was 0.53 per 1,000 live births… [0.05%]
https://evidencebasedbirth.com/groupbstrep/
Whatever the testing scheme, the treatment offered for a positive test is Intravenous (IV) antibiotics from the start of labour and repeated every 4 hours.
There are 3 arms to the UK GBS3 trial
- Standard Arm – where Testing is offered using the existing UK risk based approach
- Universal Arm – where testing is offered to every pregnant person between 35 & 37 weeks in an Enriched Culture Medium (ECM) and
- Rapid Testing – where testing is offered to every pregnant person at the bedside as they present to a hospital in labour
Is my hospital taking part in the study?
Maternity hospitals who are taking part in the trial have been randomly assigned to one of the 3 arms. I’ve done some digging in to our local hospitals and the following table is what I’ve discovered. If a hospital is not listed, I’ve either not considered it to be in our area, or I haven’t been able to find a definitive answer. If you know information I haven’t been able to find, please comment below and I’ll update the table. The study’s map of involved hospitals is here.
If your hospital IS taking part in the study, whichever arm they are in, there should be posters and information clearly displayed in ante-natal and other clinics where pregnant people congregate.
| Standard Arm | Universal Arm | Rapid Testing Arm | Not in the study |
| Chester – Countess of Chester | Crewe – Leighton Maternity | Warrington – Warrington & Halton | Stoke – Royal Stoke University Hospital |
| Stockport – Stockport NHS Foundation Trust (Stepping Hill) | Rhyl – Glan Clwyd Hospital (assumed based on linked article) | Mold – Preswylfa, Betsi Cadwaladr University Health Board | Wrexham Maelor |
| North Manchester General Hospital | Anywhere in Shropshire | ||
| Blackpool Teaching Hospitals | Liverpool Womens | ||
| Wirral Women & Children’s Hospital | |||
| Whiston General Hospital | |||
| Southport & Ormskirk | |||
| Blackburn – East Lancashire Hospital Trust |
These hospitals are in the trial but I’ve yet to discover which arm they are in:
- St Helens and Knowsley Teaching Hospitals NHS Trust
- Manchester Royal Infirmary, Manchester University NHS Foundation Trust (St Mary’s) – messaged 8/1/24
- Royal Oldham Hospital
- Bolton NHS Foundation Trust
- Southport and Formby District General Hospital
- Royal Preston Hospital
update March 2024 – I cannot find evidence on the ELHT (Blackburn) website that they are taking part in the GBS3 trial – but they are in the iGBS trial – which is a different study listed on their research page under the Children’s section, and now I need to go and look up that one!
Do I have to be part of the study if my hospital is taking part?
The short answer is NO
The longer answer: Whether your maternity care is being provided by a hospital that is in the trial or not, any test or treatment for GBS is an offer that you actively decline or consent to. That’s even true of the tests they conduct when you hand over urine at a routine appointment. If you want to know, ask them what they’re testing for, and if you don’t want them testing for GBS let them know!
Just because your hospital is in the trial you DO NOT have to have any tests or procedures you do not want to have. You can accept the test and decline antibiotics for example, or decline the test at the outset. Every step of the testing/treatment pathway is a choice that YOU and only YOU make.
You will be asked for verbal consent only before providing a swab. The swab is of your rectum and/or vagina and is performed by you or a midwife/medical professional if you prefer.
If you decline any part of the testing/treatment option and your hospital is in the trial your data and your baby’s data may still be included in the trial. Outcomes for not being tested and or not accepting antibiotics in labour are still outcomes that may prove relevant to the researchers. If you do not want your data included in the study at all you will need to withdraw your consent here. Please be aware that this will withdraw your data from all NHS research and planning, not just for the GBS3 trial.
What are the risks of taking part?
Risks:
The swabbing may be mildy uncomfortable but there is no foreseeable risk of harm to either you or your baby.
As with all medications, there is a risk of a drug reaction from the antibiotics you may be offered if your test results for group B Strep are positive. However, these antibiotics are approved for use in the UK and the side effects are well known.
GBS3 Trial Website – About the GBS Trial
There are other things that might be called risks that you might want to consider.
The standard antibiotic prescribed is penicillin so if you know that you have an allergy to penicillin and you want to accept the treatment, you must inform your care providers and an alternative antibiotic will be prescribed.
If you choose to be tested and to accept IV antibiotics in labour, this may well have an impact on your choice of place of birth, particularly if you are planning a Home Birth. I have yet to be given a definitive answer on this, but it seems likely that Home Birth is off the table if you want the antibiotics and depending on your hospital/individual care provider there may be also a discussion about whether or not you can birth in water.
Vaginal Exams or anything else placed in your vagina while you are in labour – especially if your waters have broken – could increase the chance of an early onset infection if you are GBS+ whether you know that or not. Vaginal examinations, can also be declined of course, but are an integral part of hospital maternity care such that you might find it harder to decline these in the hospital where you are birthing.
Regardless of which arm of the study your hospital is in, you might be offered a GBS test anyway – a recent experience of a client in a Standard Arm hospital provides the background for this comment, when she was told, without her asking, that she could have a GBS test if she wanted one, even though that isn’t the protocol for that arm of the study.
Research has shown that IV antibiotics negatively effects the infant microbiome, but by 1 year of age most of the differences were gone especially if the infants are breastfed for at least 3 months. Research is still needed to determine if there are any long-term immune effects associated with the temporary reduction in beneficial bacteria. (Evidenced Based Birth)
My hospital is not in the study but I want to be tested for GBS.
The best place to go for information about this is The Group B Strep Support Organisation, who describe how you can access a GBS test if you want one outside of the UK’s risk factor testing guidance.
How long is the study?
The GBS3 trial website currently (November 2023) states that the timeline for the study is being updated, but the general information states a 62 month length with 12 months of recruiting (hospitals). The recruiting date is said to end in March 2024. So the trial will be around for a few years yet.
What don’t you know?
I don’t know if the rapid testing option is available for Home Births but given the above about place of birth I suspect that it is not. I do not know how the rapid testing hospitals are responding to Home Birth plans in respect of this.
I don’t know what will happen to GBS testing in the period between when the trial ends, and results being published.
Melanie English 