Group B Strep can be confusing during pregnancy in the UK because it is common and usually harmless, yet it can occasionally cause serious illness in newborn babies. At the same time, routine screening is not offered to everyone by the NHS. That leaves many parents-to-be wondering whether they should arrange a test themselves.
As of 2026, the UK National Screening Committee still does not recommend universal antenatal screening for Group B Streptococcus (GBS). The NHS mainly uses a risk-based approach, while private testing remains available for people who want more information about their carriage status.
What Group B Strep means during pregnancy
Group B Strep is a type of bacteria that can live in the digestive tract, rectum or vagina without causing symptoms. Carrying it does not mean you have a sexually transmitted infection, and it is not a sign of poor hygiene. Most people who carry GBS never know it is there.
During pregnancy, the concern is that the bacteria can occasionally pass to a baby around labour and birth. The NHS estimates that GBS causes illness in about 1 in 1,750 pregnancies. Most babies remain healthy, but early-onset infection can cause sepsis, pneumonia or meningitis.
Why the NHS does not routinely test everyone
The NHS group B strep policy can seem surprising, especially because some countries use routine late-pregnancy screening. In the UK, the National Screening Committee currently lists antenatal GBS screening as not recommended.
One reason is that GBS carriage can change. Someone may test positive several weeks before birth and no longer carry the bacteria in labour, or test negative and acquire it later. Universal screening could also lead to many people receiving antibiotics in labour even though their babies would never have developed GBS infection. The committee has judged that the evidence has not shown that the overall benefits of universal screening outweigh the potential harms.
GBS may be discovered through a urine test or swab taken for another reason, and maternity teams also consider recognised risk factors and pregnancy history.
When NHS testing or treatment may be discussed
If GBS is found in your urine, vagina or rectum during the current pregnancy, tell your midwife or obstetric team. A GBS urinary infection is treated during pregnancy, and antibiotics in labour are also usually offered. If GBS is found only on a vaginal or rectal swab, antibiotics are generally not given simply to clear carriage before labour.
RCOG guidance gives particular attention to people who carried GBS in a previous pregnancy. If a previous baby was not affected, an enriched culture medium, or ECM, swab may be offered at 35 to 37 weeks to help guide the decision about antibiotics in labour. If a previous baby had GBS disease, antibiotics in labour are normally recommended in later pregnancies.
What to know about a private GBS test in the UK
A GBS test private UK service is an option if routine NHS testing is not available and you want to know whether you are carrying the bacteria close to your due date. The ECM test uses swabs from the low vagina and rectum and a laboratory process designed specifically to detect GBS carriage.
Testing is commonly timed at around 35 to 37 weeks because the result is more useful close to birth. Private services may provide a home sampling kit that is posted to a laboratory, although price and turnaround time vary. Before ordering, check that the laboratory is appropriately accredited and that the test is intended to detect GBS carriage.
Discuss testing with your midwife before paying privately. Ask whether your maternity unit can offer an appropriate test based on your history and how it would record and act on a private result.
What a positive result really means
A positive result means GBS was present when the samples were taken. It does not mean your baby is infected, and it does not mean you are ill. Most babies born to GBS carriers do not develop infection.
The main change is usually planning for labour. RCOG advises that intravenous antibiotics during labour can reduce the risk of early-onset infection substantially. Its patient information gives an approximate reduction from around 1 in 400 to around 1 in 4,000 for a baby whose mother is known to carry GBS.
For example, imagine you take an ECM test at 36 weeks and it is positive. Show the result to your midwife, make sure it is recorded in your maternity notes, discuss where you plan to give birth, and confirm when to contact the unit once labour starts or your waters break. If you have a penicillin allergy, mention it in advance so an alternative can be considered.
What a negative test can and cannot tell you
A negative result can be reassuring, but it cannot reduce the strep B baby risk to zero. Carriage can change between testing and birth, and reliability depends on how the samples were taken and processed. This is why timing and test method matter.
Your maternity team will still assess events in labour. Premature labour, fever, waters breaking well before birth and other clinical concerns can affect decisions about antibiotics or newborn observation even without a known positive result.
Questions to discuss with your midwife
Ask whether GBS has already been found in any urine or swab result, whether your previous pregnancy history changes the recommendation, whether an ECM test is available through your NHS maternity service, and how a private result should be shared. You may also want to read about pregnancy screening tests and preparing a birth plan.
Frequently asked questions
Is Group B Strep routinely tested for during pregnancy in the UK?
No. Routine screening for all pregnant people is not currently recommended. GBS may be found during other tests, or specific testing may be discussed depending on your history and maternity care.
When is the best time to take a private GBS test?
For most people choosing an ECM test, 35 to 37 weeks is commonly recommended because it gives a better indication of carriage status close to birth.
Does a positive GBS test mean I need antibiotics immediately?
Not usually if GBS is found on a vaginal or rectal swab and you are otherwise well. Antibiotics are generally offered intravenously during labour. GBS found in urine is different because a urinary infection may need treatment during pregnancy too.
Can I still have a healthy baby if I test positive?
Yes. Most babies of people who carry GBS are born healthy. A positive result mainly helps your maternity team plan steps that can further reduce the chance of early-onset infection.
Making the decision with better context
Group B Strep testing in pregnancy in the UK is not a simple choice between “tested means safe” and “not tested means risky.” The NHS uses a risk-based approach, while private ECM testing can provide additional information for parents who want it. Base the decision on your pregnancy history, the timing and quality of any test, and a clear plan for a positive result. Share any private result with your midwife so it becomes part of your maternity care.