Group B Strep is the most common cause of life-threatening infection in newborn babies in the UK. It causes sepsis, meningitis and pneumonia. In the UK:

  • 2 babies a day develop group B Strep infection
  • 1 baby a week dies from group B Strep infection
  • 1 baby a week recovers from group B Strep infection with disability

Despite this, we know many new and expectant parents struggle to find the information they want on group B Strep. Here we give a brief overview of group B Strep, what it can mean in pregnancy and after a baby is born.

What is group B Strep?

Group B Strep is a bacterium which lives normally and naturally in and on humans without causing harm or symptoms. This is often described as ‘carrying’ or ‘being colonised’ with group B Strep.

About 1 in 4 pregnant women carry group B Strep bacteria without any symptoms. This is perfectly normal: carrying group B Strep isn’t a sign of poor hygiene and it is not a sexually transmitted disease.

Carrying group B Strep isn’t harmful to an adult, but it can affect newborn babies around labour and birth. It’s possible for group B Strep to affect the baby during pregnancy, but this is very rare.

Why would I want to know I’m carrying group B Strep?

If you’re carrying group B Strep bacteria around the time you give birth, there’s about a 50/50 chance your baby will be exposed to the bacteria. Most babies will be fine, but about 1-2% of these babies will fall seriously ill with sepsis, meningitis or pneumonia.

However, if you know you’re carrying group B Strep late in pregnancy, you can have simple, safe and effective antibiotics in labour. These antibiotics, given intravenously (through a vein) from the start of labour, can reduce the chance of your newborn baby developing group B Strep by about 80-90%.

If you carry group B Strep and DON’T have the intravenous antibiotics in labour, the chance of your newborn baby developing a group B Strep infection is about 1 in 400 (0.25%).

If you carry group B Strep and DO have the intravenous antibiotics in labour, the chance of your newborn baby developing a group B Strep infection is about 1 in 4000 (0.025%).

How can I tell if I’m carrying group B Strep?

Carrying group B Strep has no symptoms, so the only way to tell if you are carrying it is to test for it. The NHS does not currently offer a test for group B Strep carriage to all pregnant women (although most developed countries do).

Testing is simple and safe, and there is a test specifically designed to detect group B Strep carriage – the ECM or Enriched Culture Medium test which is becoming increasingly available within the NHS.

You can test privately from £35. We have a curated list of reputable providers of the group B Strep test at www.gbss.org.uk/test.

Group B Strep carriage status can change, so it’s best to take the test in the last 3-5 weeks of pregnancy, so at 35-37 weeks’ gestation for most women.

I’ve got my test results, what do I do now?

When you get your results, it’s important to make sure your midwife or doctor has a copy of the results, so they can add them to your notes.

If your result is positive for group B Strep, you’ll be offered intravenous antibiotics in labour or when your waters break. This is usually Penicillin, which is a safe, narrow-spectrum antibiotic which is very effective against group B Strep. It’s very important to let your midwife or doctor know if you’re allergic to Penicillin as alternatives are available.

I want to learn more about group B Strep, where do I go?

If you want more information about group B Strep, we’d suggest reading through our page on group B Strep in pregnancy and newborn babies.

You may also want to download or order a free print copy of our leaflet on group B Strep, co-written with the Royal College of Obstetricians and Gynaecologists.

If you’ve still got questions, do email the charity on [email protected] or call our Helpline on 0330 120 0796