Group B strep is a type of bacteria called streptococcal bacteria. It's very common in both men and women and is usually completely symptom-less and harmless.

While this bacterium is normal and natural, and doesn't require treatment on its own, in pregnancy it deserves more notice.

Group B Strep in pregnancy

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

However, if you're a carrier of Group B Strep, there's a risk of passing it to your baby during labour and making your baby unwell. This happens in around 1 in 1,750 pregnancies.

At the moment, it's not routinely tested for in the UK - because it's common and testing can't predict if your baby will be infected - but it may be found during tests carried out for another reason, such as a urine test or vaginal swab.

What happens if I have Group B Strep?

All UK national guidelines recommend that you should be offered intravenous antibiotics in labour as this can significantly reduce the risk of your baby becoming unwell. These antibiotics reduce the risk of your baby developing a GBS infection in their first week of life from around 1 in 400 to 1 in 4,000. Let your midwife know you've tested positive so they can ensure you get the correct care.

You may be advised to:

  • discuss your birth plan – they may recommend giving birth in hospital.
  • contact your midwife as soon as you go into labour or your waters break.
  • stay in hospital for at least 12 hours after giving birth so your baby can be monitored, though this is not always necessary.

Can I get my own Group B Strep test?

Absolutely, private tests are available and cost around £55 (as of May 2024).

If you're worried, speak to your midwife about the risks to your baby, and ask their advice about whether to get tested.

The ECM test is considered the ‘gold standard’ for detecting Group B Strep and is simple, safe and effective.

If you decide to order the test privately, you should aim to test within the last 5 weeks before you're due to give birth (between 35-37 weeks’ of pregnancy).

You can test earlier, but the test result is not as reliable at predicting what your carriage status will be (positive or negative) when you give birth. The test can also be done later, but the chance increases that the baby will arrive before the test result does. If you have a history of going into labour early or are expecting twins (or more), you may want to take this into account when doing your group B Strep test.

What could GBS mean for my baby?

The vast majority of babies that come into contact with GBS make a full recovery with early treatment.

However, some babies become seriously ill, usually within 12-24 hours of their birth. This is known as early-onset GBS infection. They'll be given antibiotics into a vein if they develop symptoms.

GBS infection is rare after the first 2 days of a baby’s life and very rare after they are 3 months old.

UK charity Group B Strep support have more information. Their leaflet Group B Streptococcus (GBS) in pregnancy and newborn babies is available in 14 languages. 

More Resources

Group B Strep Support

NHS Website

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