This is a hot topic, partly because the practice of testing for GBS in pregnancy here in the UK is different to the USA, and I lose track of how often I get asked by women if they should pay to have this test privately!
This post will help you understand what exactly is meant by the term GBS, what tests are available and why there are differences in practice!
All advise and statistics are taken directly from the RCOG Green Top guideline.
What is GBS?
🔬GBS is a common bacteria, part of the Streptococcus family, usually found in the vagina and rectum
🔬20-40% of women carry it at any time. Carrying it is not harmful to you and it does not cause symptoms. It also comes and goes, so it may be present for a few weeks and dissapear for a while.
🔬It is more commonly carried in Black African women, and less common in women of South Asian descent
Why does it matter?
🔬GBS can be passed to your baby at the time of birth and so can cause infection in newborns.
🔬The main concern is that newborns can develop Early Onset GBS infection (EOGBS) which is extremely rare, but can result in infant mortality or ongoing disability in a small proportion of babies who contract this illness.
🔬Affects around 1 in 2000 babes in the UK per year
🔬May cause sepsis, pneumonia or meningitis
🔬Of those who contracted EOGBS in 2015, 22% of the babies had been born preterm, and 35% had some form of risk factor.
Who is at higher risk?
🔬Women who have previously had a baby with GBS infection
🔬Any positive GBS swabs/ cultures during pregnancy
🔬Preterm labour
🔬Preterm rupture of membranes or infection during labour
What tests are available?
🔬GBS can be found by swabbing the vagina, rectum or in urine samples.
🔬Women in the UK are not routinely tested – the test may be done if you need the above swabs for any other reason eg unusual discharge, urine symptoms etc.
🔬Women who have had previous GBS in pregnancy will be routinely tested at around 36 weeks
🔬There is a private test available and there is more information on this on the Group B Strep Support charity website.
What about in the US?
In the USA all women are screened for GBS between 35-37 weeks
If I am GBS positive, what will that mean?
🔬If found to have GBS you will be offered antibiotics via drip once in labour or after waters have broken
🔬Babies who are found to have GBS infection will be treated with antibiotics which usually cures the infection effectively.
Why aren’t women routinely screened in the UK?:
The UK National Screening Committee does not recommend testing all pregnant women for GBS carriage because:
🔬20-40% of all women carry GBS and despite this, the vast majority of babies are born safely without infection
🔬GBS comes and goes so testing positive once doesn’t mean it will still be there at birth. In fact, 25% of the women who test postive between 33-37 weeks will be negative at delivery, and up to 7% of those who are negative at screening are positive at delivery.
🔬Giving antibiotics to all women who carry GBS would mean a large number of women would receive treatment, with potential side effects, that they do not need.
🔬Many of the babies who are seriously affected by GBS infection were born preterm, before the suggested time for testing (35-37 weeks)
What if I was GBS positive in a previous pregnancy?
🔬This gives a 50% chance of being a carrier again. Therefore you will automatically qualify for testing at 35-37 weeks of pregnancy
What if I had a baby who developed a GBS infection?
🔬In this situation, you will automatically qualify to be offered antibiotics in labour, regardless of whether your screening result is positive or negative.