Group B strep

What is group B strep?

Group B strep is a type of bacteria called streptococcal bacteria.

It's very common – up to 2 in 5 people have it living in their body, usually in the rectum or vagina.

It's normally harmless and most people won't realise they have it.

It's usually only a problem if it affects:

• pregnant woman – it could spread to the baby
• young babies – it can make them very ill
• elderly people or those who are already very ill – it can cause repeated or serious infections

This page focuses on group B strep in pregnancy and babies.

Group B strep in pregnancy

Group B strep is common in pregnant women and rarely causes any problems.

It's not routinely tested for, but may be found during tests carried out for another reason, such as a urine test or vaginal swab.

Risks in pregnancy

If you have group B strep while you're pregnant:

• your baby will usually be healthy
• there's a small risk it could spread to your baby during labour and make them ill – this happens in about 1 in 1,750 pregnancies
• there's an extremely small risk you could miscarry or lose your baby

What to do if you're worried

If you're worried about group B strep, speak to your midwife or GP for advice.

Talk to them about the risks to your baby and ask their advice about whether to get tested.

Routine testing isn't currently recommended and tests are rarely done on the NHS, but you can pay for one privately.

You can find information about getting tested for group B strep on the Group B Strep Support website.

What happens if you have group B strep

If tests find group B strep, or you have had a baby that's been affected by it before, you may need extra care and treatment.

You may be advised to:

• speak to your midwife about your birth plan – they may recommend giving birth in hospital
• contact your midwife as soon as you go into labour or your waters break
• have antibiotics into a vein during labour – this can significantly reduce the risk of your baby getting ill
• stay in hospital for at least 12 hours after giving birth so your baby can be monitored – this isn't always necessary

Group B strep in babies

If you had group B strep during pregnancy, there's a small risk it could spread to your baby and make them very ill.

If this happens, it's usually soon after they're born. Your baby may be monitored in hospital for up to 12 hours to check for any problems.

They'll be given antibiotics into a vein if they develop symptoms.

What to look for after leaving hospital

Occasionally, symptoms of a group B strep infection can develop up to 3 months after birth.

Call 999 or go to A&E if your baby gets any of these symptoms:

• being floppy and unresponsive
• grunting when breathing
• an unusually high or low temperature
• very fast or slow breathing
• a very fast or slow heart rate

They may need treatment with antibiotics in hospital immediately.

Risks in babies

Most babies with a group B strep infection make a full recovery if treated.

Some babies may develop serious problems like sepsis or meningitis.

This can cause lasting problems like hearing loss or loss of vision. Sometimes it can be fatal.

More information

For more information and advice about group B strep, see:

• Royal College of Obstetricians and Gynaecologists: group B streptococcus in pregnancy and newborn babies (PDF, 425kb)
• Group B Strep Support – a charity for people affected by group B strep

Page last reviewed: Mon Feb 2021 Next review due: Mon Feb 2021