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Group B Streptococcus

What is it? What are the symptoms? What are the treatments?

What is Group B streptococcus?

Group B streptococcus (also known as group B strep or GBS) is a type of bacteria that men and women both carry normally. About 25% of women carry it in their vaginas, and although it's harmless and symptomless, it can become a problem during labour and delivery, because it can be transmitted to the baby. GBS is thought to be the most common cause of bacterial infection of newborns, and in 90% of cases it becomes apparent in the first 12 hours after birth. It doesn't develop in all babies whose mums have GBS at the time of delivery, but in rare cases it can be fatal.

There's currently no nationwide screening programme for GBS, so many mums-to-be won't know they have it unless they've had a vaginal swab test for something else or it's been picked up in their urine – in which case it should have been treated with antibiotics at the time. Also, it's not always active, so even if a swab test, which is offered by some NHS Trusts, does come back negative, it doesn't necessarily mean GBS won't be present during the birth. You're more at risk of infecting your baby with GBS if:

  • your labour is premature (before 37 weeks of pregnancy)
  • you have a raised temperature in labour
  • your waters break 18 hours or more before delivery
  • you've previously had a baby infected with GBS
  • GBS has been discovered in your vagina during a routine test
  • GBS has been found in your urine.

What are the symptoms of Group B streptococcus?

The condition is symptomless in adults, but if it develops in babies, symptoms include: grunting; irritability; listlessness; low blood pressure; high or low temperature, heart rate or breathing rate. 'Late onset' GBS, which is rare and develops when baby is 6 days to 3 months old, usually develops as meningitis with septicaemia.

What are the treatments and remedies of Group B streptococcus?

If an expectant mum is found to have GBS in her vagina, the normal treatment is intravenous antibiotics (given through a vein) from when labour begins or her waters break until delivery. This prevents infection of the baby in the vast majority of cases. Depending on the individual case, the newborn may be given intravenous antibiotics too.

This guide 

The information in this Bounty A-Z of Family Health is not a substitute for an examination, diagnosis or treatment by a doctor, midwife, health visitor or any other qualified health professional. If in doubt, always speak to a doctor.

Bounty will not be held responsible or liable for any injury, loss, damage, or illness, however this occurs or appears, after using the information given on this website and in particular the A-Z of Family Health.

Further help

For health advice and information 24 hours a day, 365 days a year, the NHS offers call and web services. You can also visit NHS websites for services, health information and health news at nhs.uk 

  • England – call 111 from any landline or mobile phone free of charge, or visit nhs.uk 
  • Scotland – call 111 from any landline or mobile phone free of charge, or visit nhs24.com 
  • Wales – call 0845 4647 , or visit nhsdirect.wales.nhs.uk 
  • Northern Ireland – visit hscni.net


Group B Streptococcus