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 bottom (rectum) or vagina. It affects 2 to 4 women in 10.
Group B strep is normally harmless and most people will not realise they have it.
It's usually only a problem if it affects:
This page focuses on group B strep in pregnancy and babies.
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.
If you have group B strep while you're pregnant:
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 is not currently recommended and tests are rarely done on the NHS, but you can pay for one privately.
If tests find group B strep, or you've had a baby that's been affected by it before, you may need extra care and treatment.
You may be advised to:
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.
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:
They may need treatment with antibiotics in hospital immediately.
Most babies with a group B strep infection make a full recovery if treated.
This can cause lasting problems like hearing loss or loss of vision. Sometimes it can be fatal.