Group B Strep

Group B Streptococcus, usually shortened to GBS, is a type of bacteria that naturally lives in the digestive system and can also be found in the vagina. For most people, it causes no problems at all. In a small number of newborn babies, however, GBS can cause a serious infection around the time of birth. This is why you may hear about GBS during pregnancy and why some people are offered antibiotics during labour. The good news is that most babies born to people who carry GBS are completely well.

Understanding what GBS actually is, what your individual risk looks like and what your options are can make the whole subject feel much less alarming.

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What is Group B Strep?

 

GBS is one of many bacteria that can normally live in our bodies without causing any harm. Around 20 to 40% of women in the UK carry GBS, usually in the vagina or rectum, without having any symptoms. Being a GBS carrier:

• isn't an illness

• usually causes no symptoms

• isn't a sexually transmitted infection

• doesn't mean that anything is wrong with you

• doesn't mean that your baby will become infected

 

You can carry GBS at one point and not at another. It can come and go naturally.

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Why does GBS Matter in Pregnancy?

 

Although GBS is usually harmless to the person carrying it, a baby can occasionally develop a serious GBS infection around the time of birth. This is called early-onset GBS infection when it occurs during the first week of life. It can cause infections including:

• sepsis

• pneumonia

• meningitis

 

Early-onset GBS infection is rare. In the UK and Ireland, around 1 in every 1,750 newborn babies is diagnosed with it.

So while GBS is something maternity teams take seriously, carrying GBS does not mean that your baby is likely to become ill.

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How would I know if I carry GBS?

 

This is where things can get a little confusing in the UK. The NHS does not currently offer routine GBS screening to every pregnant woman. This is because GBS is very common, and testing at one point in late pregnancy cannot reliably predict whether someone will still be carrying GBS when their baby is born. A negative test also cannot guarantee that GBS isn't present at the time of birth.

GBS may nevertheless be discovered during pregnancy. For example, it might be found:

• in a urine sample

• on a vaginal or rectal swab

• during investigations for another reason

 

Some people also choose to have a private GBS test during pregnancy. If you're considering private testing, it's worth discussing what type of test is being offered and what the result would mean for your care.

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What Happens if I Test Positive?

 

If GBS is found during your current pregnancy, you will usually be offered antibiotics through a drip during labour to reduce the chance of your baby developing early-onset GBS infection. You don't usually need antibiotics simply because you carry GBS before labour begins.

This is because treating GBS while you're pregnant does not reliably remove the bacteria. It can return, and giving antibiotics before labour doesn't reduce the risk of early-onset GBS infection in the same way that antibiotics given during labour do.

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What if GBS is found in my urine?

If GBS is found in your urine during pregnancy, this is treated as a GBS urinary infection if treatment is clinically indicated. You should also be offered antibiotics during labour because the presence of GBS in your urine indicates a higher level of colonisation. Your maternity team will explain what treatment you need.

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What if I've had a Baby with GBS Infection Before?

 

If you have previously had a baby who developed an invasive GBS infection, you should be offered antibiotics during labour in future pregnancies. This is because the risk of GBS infection is higher in a subsequent baby. This is different from simply having tested positive for GBS in a previous pregnancy. If you carried GBS previously but your baby was unaffected, your maternity team can discuss whether testing later in the current pregnancy would be useful.

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What Increases the Risk to my Baby?

 

The chance of early-onset GBS infection is higher in certain circumstances. These include:

• your baby being born prematurely, before 37 weeks

• having had a previous baby affected by GBS infection

• having a high temperature or other signs of infection during labour

• GBS being found in your urine or on a swab during the current pregnancy

• your waters being broken for more than 24 hours before your baby is born

 

This is why your maternity team will consider the whole picture rather than simply asking whether you have ever carried GBS.

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What are the Antibiotics in Labour?

 

If you're offered antibiotics because of GBS, they are usually given through a drip into a vein once labour starts or your waters break.

NICE recommends giving the first dose as soon as possible after labour starts, and continuing antibiotics at regular intervals until your baby is born. The aim is to reduce the amount of GBS your baby is exposed to during birth. RCOG estimates that antibiotics during labour reduce the risk of early-onset GBS infection from around 1 in 400 to around 1 in 4,000 for someone known to carry GBS.

That's a reduction in an already small risk.

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Does having GBS mean I need to give Birth in Hospital?

 

Not necessarily, but it can affect your options depending on your circumstances and local maternity service. If you're planning a home birth or birth in a midwife-led unit and have been advised to have intravenous antibiotics during labour, it's worth discussing this with your maternity team before labour begins. Some birth settings may not be able to provide intravenous antibiotics. Ask your maternity team what is available locally and how GBS would affect your planned place of birth.

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What if my Waters Break Before Labour?

 

If you're known to carry GBS and your waters break after 37 weeks, your maternity team may recommend induction of labour rather than waiting for labour to begin naturally. The reason is to reduce the amount of time your baby is exposed to GBS before birth. You would also be offered antibiotics during labour. If your waters break and you know you carry GBS, contact your maternity team promptly and tell them that you are GBS positive. If you're not known to carry GBS, your maternity team will assess you according to the circumstances, including how long your waters have been broken and whether there are any signs of infection.

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What if I go into Labour before 37 weeks?

 

If labour starts before 37 weeks, antibiotics during labour are generally recommended because being born prematurely is itself a risk factor for early-onset neonatal infection. Your maternity team will assess you and your baby and explain what is recommended.

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Does it mean I can't have the birth I want?

 

No. Being GBS positive doesn't automatically mean you need an induction, a caesarean or a particular type of birth.

It does mean that there may be some additional considerations around when your waters break, where you give birth and whether you have antibiotics during labour. If antibiotics are recommended, you can still discuss your birth preferences with your maternity team.

For example, you might want to ask:

• Can I still move around during labour?

• Can I use the pool?

• Can I use gas and air or other pain relief?

• Can I still use my preferred birth positions?

• How will the antibiotics be given?

• How often will I need them?

• What happens if labour progresses quickly?

• Can I still have a home birth or use a midwife-led unit?

 

The practical details can vary between maternity services, so it's worth asking your own team.

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What if I don't want antibiotics?

 

If antibiotics during labour are recommended for you, your maternity team should explain why they are being offered, what they are intended to do and what the alternatives and possible consequences are. You can ask questions about the recommendation and discuss your options. For any decision about your care, useful questions include: What are my options? What are the benefits and downsides of each option for me and my baby? What would happen if I chose not to have the recommended treatment? This isn't about finding the "right" answer. It's about understanding the decision you're being asked to make.

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Why doesn't the NHS test everyone for GBS?

 

This is one of the most common questions. If GBS can occasionally cause serious infection, why not simply test everyone at 35 to 37 weeks and give antibiotics to everyone who tests positive? The reason is that the UK has a risk-based approach rather than routine universal screening. There are several reasons for this:

• GBS is very common.

• Carrying GBS doesn't usually cause any problems.

• A test only tells us whether GBS was detected at that particular point in time.

• A negative test doesn't guarantee that GBS won't be present at birth.

• Some babies who develop early-onset GBS infection are born prematurely, before routine late-pregnancy screening would take place.

• Giving antibiotics to everyone who tests positive would mean many people receiving antibiotics even though their babies would never develop a GBS infection.

 

The UK approach is therefore based on a combination of known GBS carriage and other risk factors.

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What Happens to my Baby after Birth?

 

Most babies born to people who carry GBS are completely well. If you've had antibiotics during labour and your baby is well, your baby may simply receive routine observation and care. If your baby has risk factors or develops signs that could indicate infection, the neonatal team may recommend additional monitoring, tests or antibiotics. Signs of possible GBS infection in a newborn can include:

• unusual sleepiness or difficulty waking

• not feeding well

• being unusually floppy

• grunting or difficulty breathing

• changes in temperature

• changes in skin colour

• being unusually irritable or crying inconsolably

• an unusually fast or slow heart rate or breathing rate

 

If your baby seems unwell, seek urgent medical attention and tell the healthcare professional that you were known to carry GBS.

Early treatment of suspected infection is important.

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Can I breastfeed if I'm GBS positive?

 

Yes. GBS does not mean you cannot breastfeed. Breastfeeding has not been shown to increase the risk of GBS infection and has many benefits for both you and your baby.

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Questions you Might want to Ask

 

If you've been told that you carry GBS, you could ask:

• Where was GBS found?

• Was it found in my urine or on a swab?

• What does this result mean for my pregnancy?

• Do I need treatment now?

• Will I be offered antibiotics during labour?

• What happens if my waters break before labour?

• Does this affect where I can give birth?

• Can I still use the birth pool?

• Can I still move around during labour?

• What happens if labour progresses too quickly for me to have several doses of antibiotics?

• How will my baby be monitored after birth?

• What would happen if I chose not to have antibiotics?

• Is there anything I need to do differently during pregnancy?

 

And if you're considering paying for a private GBS test, ask: "What will the result actually change about my care?" That's a useful question for any test.

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The Important Bits to Remember

• Group B Strep is a common bacteria that many healthy people carry without symptoms.

• Carrying GBS isn't an illness or an STI.

• Most babies born to people who carry GBS are completely well.

• Early-onset GBS infection in newborn babies is rare, but can be serious.

• The NHS does not currently offer routine universal GBS screening during pregnancy.

• If GBS is found during your current pregnancy, you will usually be offered antibiotics during labour.

• Antibiotics are given during labour rather than simply treating GBS earlier in pregnancy because this is more effective at reducing the risk to your baby.

• GBS doesn't automatically mean you need an induction or caesarean.

• It may affect your plans around where you give birth and what happens if your waters break.

• If you're known to carry GBS, contact your maternity team promptly when labour starts or your waters break.

• Your baby can be monitored after birth if there are risk factors or signs of infection.

• You can breastfeed if you carry GBS.

 

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Explore Next

 

Understanding Your Options
Explore common recommendations and decisions during pregnancy and birth, and the questions you can ask before making them.

 

When to Seek Help
Know when to contact your maternity team, including what to do if your waters break or you go into labour.

 

Induction of Labour
Understand why induction may be recommended, what it involves and what questions you can ask.

 

Preparing for Birth
Explore ways to prepare for labour and birth, whatever your circumstances.

 

Questions to Ask About Tests
A practical list of questions to help you understand why a test is being offered and what the results might mean.