Intended for healthcare professionals

Practice Uncertainties

Should all pregnant women be offered testing for group B streptococcus?

BMJ 2021; 373 doi: (Published 26 April 2021) Cite this as: BMJ 2021;373:n882
  1. Kate F Walker, clinical associate professor of obstetrics1,
  2. Jane Plumb, chief executive2,
  3. Jim Gray, consultant microbiologist3,
  4. Jim G Thornton, professor of obstetrics and gynaecology1,
  5. Anthony J Avery, professor of primary health care1,
  6. Jane P Daniels, professor of clinical trials1
  1. 1University of Nottingham, Nottingham, UK
  2. 2Group B Strep Support, Haywards Heath, UK
  3. 3Birmingham Women’s and Children’s NHS Foundation Trust, Birmingham, UK
  1. Correspondence to K Walker kate.walker{at}

What you need to know

  • Many countries have guidelines that recommend universal testing for group B streptococcus (GBS) in late pregnancy so that women who are colonised with GBS receive intrapartum antibiotic prophylaxis to prevent newborn GBS infection

  • Observational studies suggest that routine testing in pregnancy reduces the risk of early onset GBS in newborns compared with offering antibiotics to women with risk factors for GBS transmission, or no testing. However, those observational studies have a moderate to critical risk of bias, and no randomised trials of routine testing versus a risk factor based approach have taken place

  • Routine testing could result in a large number of women receiving antibiotics unnecessarily, resulting in potential harms of widespread antibiotic use at individual and population levels

  • Offer testing for GBS carriage to pregnant women as per local guidelines, and where that guidance is lacking, discuss with the woman the risks and benefits of testing, as well as how the test result could affect her delivery

Introducing routine testing for group B streptococcus (GBS) for all women in late pregnancy would likely reduce cases of early onset infection in their newborns, but might also increase the number of women given antibiotics during labour.

One in five pregnant women carries GBS in the gut or genital tract, and more than half of them will pass it to their child during pregnancy, labour (most commonly), or after birth.1 Most babies exposed to maternal GBS remain well, but one in 1750 newborns in the UK and Republic of Ireland develops early onset GBS infection, mostly pneumonia and sepsis. Each year in the UK about 40 babies die from GBS infection, and one in 14 of the survivors has a long term disability.1 Babies born preterm are at higher risk of serious infection and death.2

Low quality evidence shows …

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