Group B Strep: What All Expectant and New Parents Need to Know

When you’re expecting, or a new parent, it’s important to know about group B Streptococcus (group B Strep or GBS), which can cause serious infection in newborn babies.

Group B Strep is very common

Around one in four adults carry the bacteria, usually harmlessly, in their lower intestines and vagina. It doesn’t mean you’re sick, and it’s not a sexually transmitted disease (STD).

Group B Strep can cause serious infection, most often in newborn babies

Group B Strep is the most common cause of severe infection in newborn babies, causing sepsis (blood infection), pneumonia (lung infection) and meningitis (brain infection). The bacteria may be passed unknowingly from a mother to her baby around birth.

Most infections show within 24 hours of birth, and become less common as time passes (they are very rare after about three months). Most babies make a full recovery, but sadly not all. In the UK, on average:

  • two babies each day develop group B Strep infection;
  • one baby a week dies from group B Strep infection;
  • one surviving baby a week is left with long-term health issues like cerebral palsy or hearing or vision loss.

Most group B Strep infections can be prevented 

Most group B Strep infections in newborn babies can be prevented by testing the mother late in pregnancy and providing intravenous antibiotics during labour to those who test positive.

This can reduce the risk of a baby developing group B Strep infection by up to 90 percent.

Unfortunately, the UK does not routinely test for group B Strep, unlike the United States, Canada, Germany, France, Spain and many other developed countries where all mothers-to-be are tested. You can choose to take a private test, which costs around £35. 

The test, usually taken between 35 and 37 weeks of pregnancy, is a simple swab test. There is a specific test for group B Strep carriage, called the ECM or Enriched Culture Medium test. This is not available from all NHS hospitals, or to all pregnant women, although availability is increasing. It is available privately. The Group B Strep Support charity lists providers on its website at

Risk-factors that increase the chance of a newborn developing a group B Strep infection

If group B Strep has been detected this pregnancy or you have specific ‘risk-factors’ that increase the chance of your newborn baby developing group B Strep infection, antibiotics will be offered to you during labour. The key ‘risk-factors’ are:

  • you have previously had a baby who had group B Strep infection;
  • group B Strep has been found during this pregnancy from a urine sample, or a vaginal or rectal swab;
  • group B Strep was found in a previous pregnancy (without a negative ECM test result this pregnancy);
  • your baby is born before 37 completed weeks of pregnancy;
  • you have a high temperature during labour.

You should be provided with a leaflet about group B Strep during antenatal care

If you haven’t, ask your midwife or doctor. The leaflet, co-written by experts from the Royal College of Obstetricians & Gynaecologists and charity Group B Strep Support, can be downloaded from

If you want to know more about group B Strep, visit or call Group B Strep Support’s Helpline on 01444 416176. 

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