How To Protect Your Baby from Group B Strep (GBS) Infection

  1. What is Group B Streptococcus? Group B Streptococcus (GBS) is a very common bacterium. It occurs naturally in many people, from babies to the elderly, and typically causes no harm or symptoms. Carrying GBS (also called GBS colonisation or GBS carriage) is entirely normal - up to one in every three people carries GBS in the gut (bowel), and in women it is often also found in the vagina. Carrying GBS can be intermittent - it can come and go - and simply carrying GBS does not require treatment.
  2. What is GBS infection in Babies? GBS carriage is harmless, but the bacteria can cause infection. GBS infection (when the bacterium starts to cause harm) occurs most often in newborn babies before, during or shortly after birth - thankfully this happens relatively rarely, in only approximately one in every 1,000 babies where no preventative action is taken. However, this still means that UK wide, 700 babies a year develop GBS infection - usually septicaemia, pneumonia and/or meningitis. Most fully recover, but around 10% of babies infected with GBS die and survivors can be left with serious mental or physical disabilities.
  3. How can I protect my baby from a GBS Infection? Most newborn babies who develop GBS infection are born where recognised ‘risk factors' are present. These are:
    • The mother has previously had a baby infected with GBS - risk is increased 10 fold
    • The mother has been found to carry GBS in this pregnancy or GBS has been found in the urine at any time during this pregnancy - risk is increased 4 fold

    Any of the following clinical risk factors - risk of GBS infection is increased 3 fold

    • Labour starts or membranes rupture before 37 weeks of pregnancy is completed
    • Where the waters (membranes) have broken more than 18 hours before the baby is born
    • Where the mother has a temperature during labour of 37.8°C or higher.

    If your baby is at increased risk of developing GBS infection because one or more of the above ‘risk factors' is present, then you can consider having intravenous (through a vein) antibiotics as soon as possible from the start of labour and at intervals until labour. This is highly effective at preventing the GBS bacteria infecting newborn babies and causing septicaemia, pneumonia and meningitis.

  4. How do I find out if I am carrying GBS? You can find out if you carry GBS by having a test to detect it since you won't have any signs or symptoms if it's there. Testing for GBS carriage during pregnancy is not routine in the UK,

    There are currently two tests used in the UK to detect GBS carriage

    • The High Vaginal Swab (or HVS) or, less commonly, the Low Vaginal Swab (LVS) -A high or low vaginal swab is taken and then sent to the laboratory, where the material from the swabs are cultured using standard culturing media. This test is available on the NHS and, although a positive result from this test is highly reliable, a negative result is not. Up to half of all women carrying GBS when a standard HVS or LVS test is conducted will be given a false negative result.
    • The Enriched Culture Medium (or ECM) test - A low vaginal and a rectal swab is taken and sent to the laboratory for testing using enriched culture media, hence the name. The ECM test is considered the "Gold Standard" and is the best GBS screening available. This test is available from a handful of NHS hospitals and from two private laboratories.

    The best time to test for GBS carriage is after 35 weeks of pregnancy - GBS carriage causes no symptoms and can be intermittent. However, an ECM test result (positive or negative) will be very predictive of GBS carriage status for around 5 weeks, which is why - if you are going to test for GBS carriage - it's normally done at 35-37 weeks of pregnancy.

    Two laboratories that can offer testing by post are:

    • The Doctors Laboratory
      Tel: 020 7307 7373
      Fax: 020 7307 7374
      E-mail: [email protected]
    • Mullhaven Medical Laboratory
      Tel: 01234 831115
      Fax: 01234 831116
      Email: [email protected]

For more information about GBS, please speak with your doctor or midwife, or call national charity, Group B Strep Support on 01444 416176 or check out the website at


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