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 bacterium that men and women carry normally. About 25% of women carry GBS in their vaginas, and although carrying it is harmless, it can become a problem around birth as it can pass to the baby. GBS is the most common cause of severe infection in newborns, usually becoming apparent in the first 12 hours after birth. Most babies whose mums carry GBS infection don’t develop the infection, 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 carry it unless they've had a test for something else or it's been picked up in their urine – if found in the urine, it should be treated with antibiotics when detected. GBS carriage can come and go so that, even if you carried it in one pregnancy, it may not be present during another pregnancy. 

Your newborn baby is at higher risk of developing GBS infection 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 who had GBS infection
  • GBS has been detected from a vaginal or rectal swab test or from urine test during your current pregnancy.

What are the symptoms of Group B Streptococcus?

Carrying GBS is symptomless. If a newborn  baby develops infection, signs may include: grunting; irritability; listlessness; be unusually floppy; be not feeding well or not keeping milk down; have a high or low temperature, heart rate or breathing rate. ‘Early-onset’ GBS infection usually shows within 12 hours of birth as sepsis or pneumonia. 'Late onset' GBS infection is rarer and develops when baby is 7 days to 3 months old, usually as sepsis and meningitis. Signs of GBS infection, including late-onset GBS infection, can be found here

What are the treatments for Group B Streptococcus?

If GBS is detected during the current pregnancy, the expectant Mum should be offered intravenous antibiotics (given through a vein) as soon as possible once labour begins or her waters break and at regular intervals until delivery. Mums will also be offered the antibiotics if labour is preterm, if she had a previous baby who had GBS infection or if she has a fever in labour. If a mum carried GBS in her last pregnancy and her baby was well, she should be offered the option of having the intravenous antibiotics in labour, or testing for GBS at 35-37 weeks of pregnancy, with the antibiotics offered in labour if the test result is positive. The intravenous antibiotics in labour prevent GBS infection in the newborn baby in the vast majority of cases. 

A new information leaflet about GBS has been created by The Royal College of Obstetricians & Gynaecologists and Group B Strep Support. You can download it here.

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