Should I be tested for Group B Strep in Pregnancy?


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What is Group B Strep, why is Group B Strep a concern in Pregnancy and should you be tested for Group B Strep?

What is Group B Strep?


Group B strep is a type of bacteria called streptococcal bacteria. It's very common in both men and women and usually lives in the rectum or vagina. It affects 20-40% of women. Group B strep is normally harmless and most people will not realise they have it.


Why is Group B Strep a concern in Pregnancy?


It’s important not to worry if you are told you have Group B Strep in pregnancy for the majority of women, their baby will be born happy.


However, there is a small risk it could spread to your baby during labour and make them ill – this happens in about 1 in 1,750 pregnancies.


How common is it for babies to become unwell with GBS?


GBS is the most common cause of sepsis and meningitis in babies across most developed countries. In the UK, early onset GBS infection occurs in 0.05% of babies.


How to prevent GBS infection in babies?


If a mother is known to be GBS positive in pregnancy intravenous antibiotics are recommended during labour.


How do I know if I have GBS?


You may not. Or you may find out inadvertently due to a vaginal swab or urine sample being taken in pregnancy for another reason. Some women will choose to be tested privately for GBS as it is not routine practice in the UK.


What are the signs of GBS infection in a baby?


There are 2 type of GBS infection: early onset (0-6 days) and late onset (7-90 days)


Early onset GBS Infection:

This accounts for 2/3 of GBS infection in babies.

Typical symptoms include:

• Grunting, noisy or difficulty breathing,

• Being very sleepy /unresponsive

• Inconsolable crying

• Unusually floppy

• Not feeding well / keeping milk down

• Having a high / low temperature

• Changes in skin colour

• Abnormally fast / slow heart / respiratory rate

• Having low blood pressure/ blood sugar

It’s important to recognise these symptoms may also be something else and your health care team will be very responsive to offering treatment should any infection be suspected in a baby.


It’s also reassuring to know that most early onset GBS develops in the first 12 hours of life when you and your baby are likely still in a health care setting with 24/7 access to trained professionals observing you and your baby.


Late onset GBS Infection:

This is uncommon after 1 month of age and very rare after 3 months.


Symptoms are similar to that of early onset GBS but may also include signs of Meningitis including:


• Being irritable with high pitched / whimpering cry,

• Blank, staring expression

• May dislike being handled,

• Tense or bulging fontanelle

• Turning away from bright light

• Involuntary stiff body or jerking movements

• Pale, blotchy skin


Although testing in pregnancy and antibiotics in labour will likely prevent early onset GBS infection it has not been shown to have any impact on late onset infections.


Why isn’t GBS testing routine in the UK?


Having GBS does not mean you will definitely pass it onto your baby, it is unknown why some babies do develop GBS infection and others do not. This means the test is not a accurate predictor of early onset GBS infection in babies.


Routine screening would mean 99.8% of women who screen positive receiving unnecessary antibiotics during labour as their babies wouldn’t have developed GBS infection. This is of particular concern to the gut microbiome of mothers and babies as recent research highlights the importance of this for many health outcomes and antibiotic use is known to significantly damage this.


If I decide to have a GBS test when should I it?


Timing is important as GBS comes and goes. So, if opting to have a private test it’s ideal to have this as close to the date you go into labour as possible. Obviously, this date is hugely variable, so it is suggested 35-37 weeks to balance the reliability and doing the test before birth.


(Seedat, et al., 2019) (BMJ, 2019) (GBS.org)

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The Author: Midwife Pip

Midwife Pip

Pip is a Mum, Podcaster and practicing Midwife in the UK, currently working as a Delivery Suite Sister she has a wealth of experience supporting parents-to-be through all aspects of pregnancy, birth and the postpartum. Pip has trained and worked in some of the leading maternity units, has completed a master's programme and is passionate about all aspects of women's health and wellness.



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