Understanding Group B Streptococcus – GBS

Today, we delve into an important topic that affects many expecting parents: Group B Streptococcus (GBS). Our goal is to provide you with accurate information to support your decision making, including; what is Group B strep, it’s prevalence in the UK, what the big worry is all about, how to find out whether you have GBS (and whether you should) and how to treat it. For further guides and help during your pregnancy why not visit our resource library HERE

Understanding Group B Streptococcus:

First of all, we need to look at what GBS is. The term strikes fear into many, but why?

Bacteria are single cell organisms that are found almost everywhere on earth, including living on and in the human body. Some bacteria can be harmful, causing disease. Others helpful, aiding digestion and preventing fungal infections. Most are simply benign, neither benefiting us nor causing us harm. The delicate balance of bacteria on and in our bodies is ever changing, certain circumstances can upset this balance and change the nature of a particular bacteria from benign to harmful.

Group B Streptococcus (streptococcus agalactiae), often referred to as group B strep or GBS, is a benign bacteria that can be found in the intestines, rectum and vagina. In rare cases, GBS can cause urine, womb or other infections, however, the majority of the time, it causes no harm.

The concern surrounding group B strep comes during childbirth, as GBS bacteria can reside in the vagina and rectum, it can be passed to baby during labour and birth. Most babies will not be affected by GBS colonisation, however, this has the potential to cause illness to the newborn.

As with most bacteria, GBS can come and go throughout our lifetime and during a pregnancy. Having Group B Strep located in the vagina (for example) in early pregnancy, does not mean that it will present in that area, or at all, during labour. Like many bacteria, GBS can be passed from one person to another by skin-to-skin contact such as hand holding, kissing and close physical contact. It is not, however a sexually transmitted infection, as many people fear.

The Prevalence of GBS:

It is estimated that around 20-40% of women carry GBS bacteria on any given day, and everyday, thousands of women with GBS give birth to healthy babies. Roughly, half of the babies born to mothers with GBS will pick up (or be colonised by) GBS bacteria following birth, and mostly, these babies remain healthy and do not develop an infection.

In the UK, 1 in 1600 babies will be diagnosed with a GBS infection. Infection is higher if GBS carriage is known, with 1 in 400 babies affected. Babies that are most at risk of developing GBS infection are;

• Babies of mothers, who have had a previous child with GBS infection
• Babies born prematurely (<37 weeks gestation)
• Low birth weight babies (<2.5kg/5lb 8oz)
• Prolonged rupture of membranes (>24 hours before birth)
• Maternal high temperature in labour (38°C or higher)
• GBS found in a late pregnancy urine sample.

Infection can develop very quickly, and can cause sepsis, pneumonia and/or meningitis. Symptoms of GBS infection can include;

• Grunting, noisy breathing, moaning or seeming to be working hard to breathe
• Being very sleepy or unresponsive
• Crying inconsolably
• Being floppy
• Not feeding well or not keeping milk down
• Having a low or high temperature
• Changes in their skin colour (e.g. Blotchy/mottled skin)
• Low blood sugar
• Low blood pressure

Of course many other things can cause one or more of these symptoms too, please contact your midwife/maternity unit to rule out GBS infection.

Early onset GBS infection generally occurs within the first week of life, with 90% of cases presenting within the first 24 hours following birth. It is thought to be almost exclusively acquired during labour and birth from mothers with GBS bacteria. However, it is also possible that it can be transferred to babies if GBS bacteria is present on a surface or a practitioner the baby has had direct skin contact with, if proper sanitation is not performed. Early onset GBS infection occurs in around 1 in 1750 babies in the UK and Ireland.

Late onset GBS infection is used to describe infection that develops in babies that are one week old, up until three months of age. These infections are most usually obtained after birth and it is not preventable by administering antibiotics in labour. It is, however, somewhat preventable by ensuring that good hand hygiene is followed by anyone holding your baby. Late onset GBS infection occurs in around 1 in 2700 babies in the UK and Ireland.

Testing for GBS:

Currently, in the UK, routine testing for GBS bacteria in pregnancy is not being performed. The National Screening Committee’s view is that there is no clear evidence to show that universal testing for GBS would do more good than harm, stating that many women carry the bacteria, but in the majority of cases, babies do not develop an infection. Other reasons why routine testing has not been introduced include; screening tests for GBS are not entirely accurate, as bacteria may be present one day, but not the next, meaning that women who believe they carry GBS at birth may not, and vice versa. *Between 17-25% of women who have a positive swab for GBS at 35-37 weeks pregnant, will be negative at birth. Between 5-7% who test negative for GBS at the same gestation will have GBS bacteria at birth.

Testing for GBS can be performed by a enriched culture medium (ECM) vaginal and rectal swabs between 35-37 weeks gestation. If the ECM swabs are performed correctly within 5 weeks of birth then a negative result is 96% predictive that a woman will not be carrying GBS at birth, and if a positive result is found, this is 87% predictive that a woman would still be carrying GBS bacteria at the time of birth. ECM tests are the recommended method to test for GBS as it was specifically designed to detect GBS bacteria. These tests are usually only available privately, if families decide to seek out screening.

Most often, GBS in pregnancy is detected accidentally by high vaginal swab testing or in a urine sample, if sent for culture due to a suspected urine infection. These methods of testing are not reliable as they can miss up to a whopping 50% of cases.

Should you or shouldn’t you test for GBS? Informed Decision-Making:

Life is full of difficult choices, and so is pregnancy. Pregnancy can be an time of great joy, but it can also be overwhelming; this is no truer than when discussing GBS!

As with all tests and screening in pregnancy, everything is a choice; some families prefer to seek out GBS testing, so they can be fully informed of all their choices to make a decision that is best for them. Others prefer an ‘ignorance is bliss’ approach. There is no right or wrong way of doing things, we support personal choice, and as long as you are aware of all of your options, know the pro’s and con’s of each of them, and feel that you have made an informed decision about your care, we are satisfied.

So, why would anyone choose not to have GBS testing in pregnancy? Carrying GBS does not affect your care during the antenatal period, but it may impact on your birth choices. In the UK, if GBS is found during pregnancy (or in a previous pregnancy), intravenous antibiotic prophylaxis is offered in labour to prevent GBS transmission and subsequent newborn infection. This means that a cannula would need to be inserted into your hand or wrist, and antibiotics would be administered through it every 4 hours during labour, until the birth of your baby. No further testing for GBS is usually offered later on in the pregnancy following a positive test result, and private ECM testing results are not always accepted by hospitals. As we know from above, GBS is transient (meaning that it can come and go), so antibiotics may be given to someone who does not have GBS at the time of birth. Whilst this isn’t necessarily harmful, it may have a huge impact on birth preferences and therefore experience.

With all screening, sometimes the best thing to do to help you decide whether to do it or not, is to consider your own personal circumstances. How would you feel if you were found to carry GBS? Many people feel unclean, which we know is not the case. Would carrying GBS affect your plans for birth and how important would this be for you. Was you planning to birth at home, where you are unable to receive IV antibiotics. Did you want to use your local birthing centre, many birth centres are able to administer IV antibiotics, but this is not universally the case. Are you needle phobic and the thought of a cannula gives you the heebie-jeebies. Is freedom of movement vital to your birth experience. Whilst the antibiotic infusion doesn’t last very long, during this time, your movement may be limited to a drip pump and require your hand to remain in a certain position to ensure the administration is completed. Cannulas can be uncomfortable and this may have an impact on movement in itself. Are you concerned about the effect of antibiotics. Maybe you are overly sensitive to them or are worried about antibiotic resistance.

Everyone will have different answers to the above questions, like I said, there is no right or wrong answers. What’s important to you matters, and its these considerations that will help you decide whether seeking a test for GBS is right for you. If no test is performed then GBS is unlikely to be picked up or worried about, its unlikely that your baby will be unwell following birth even if you had GBS. Alternatively, having a negative test might give you reassurance and confidence when making your birth plan.

Antibiotic Prophylaxis:

As already mentioned, GBS is treated with intravenous (IV) antibiotics during labour. It is rarely treated during pregnancy (even if picked up early on) unless there are signs of an infection. These preventative antibiotics work in two ways; firstly, they hope to eliminate GBS bacteria from the vagina so that it can not be passed to baby during birth. Secondly, as the antibiotics cross the placenta, babies will be born with it in their system, to help treat any potentially acquired GBS infection.

IV antibiotics are administered 4 hourly from admission/established labour, until the baby has been born. Following birth, babies whose Mothers received at least one dose of antibiotics, 4 hours or more before birth, do not need any increased monitoring for infection. If IV antibiotics were not administered within 4 hours of birth, then it is usual for babies to have regular monitoring of their vital signs and behaviour for the first 12 hours of life. This may be declined if the baby presents no signs of illness.

Oral antibiotics are thought to be ineffective against GBS due to variable absorption during labour, however there is limited research detailing the effectiveness of this method and thus is rarely prescribed as a treatment to GBS.

Alternative Strategies:

There is limited research on the alternative methods of reducing GBS carriage and therefore the chance of them effectively reducing GBS infections in babies. The following are the more commonly known alternative techniques.

Vaginal douching effectively washes the vagina, in the hope of washing away GBS bacteria. Chlorhexidine is noted to be the most used solution for douching, however there is no scientific evidence to show it’s effective at removing vaginal GBS colonisation in labour. Depending on the solution used, it may cause irritation, allergic reaction, as well as the unknown effects to the natural vaginal bacteria.

Garlic pessaries are thought to reduce GBS carriage in the vagina. This is done by peeling and slightly crushing a clove of garlic and then inserting it into the vagina overnight. This is done for several nights in a row and sometimes up until the baby is born. There is great variation in the recommended process and therefore the dosage being used. As with douching, this can cause burning and irritation of the sensitive vaginal mucosa. And, again, we have no evidence to show it is effective.

In one study, water birth was found to significantly reduce GBS bacteria being passed to babies (colonising baby). This is thought to be because the babies were born underwater, any bacteria that was picked up during birth was washed off. We don’t know if this also reduces the chance of neonatal GBS infection.

What if I have tested GBS Positive But Don’t Want Antibiotic Prophylaxis?

If you have tested positive for GBS in your late pregnancy, the current recommendation is to offer you prophylactic antibiotic therapy. However, whether you accept this treatment is your choice.

If you have made a fully informed decision regarding the risks and benefits, you can decline antibiotics in labour and, in many circumstances, even have your baby at home should you wish to.

At Private Midwives we have policies to guide you and your Midwife through your options, which include recommendations for postnatal observations of your baby to look for any early signs of GBS infection.

If you think this is something you would like to consider, talk to your Midwife so that a plan can be put in place for you and your baby.

Final thoughts:

As we continue to navigate the complexities of GBS management, we keep at the forefront consideration for each individuals’ circumstances. We embrace holistic care and continue to advocate for informed decision making, working together to create safe and positive birthing experiences, whilst addressing the potential concerns of Group B streptococcus.

If you would like to see more information on Group B Strep – please see our resource library document here