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New screening trial aims to improve detection and treatment for Group B Strep in pregnant women


A landmark NIHR-funded clinical trial is aiming to improve the diagnosis and treatment of a potentially life-threatening infection in newborn babies.

The UK is one of the only countries in the developed world where there is currently no standard screening programme for the bug in pregnant women and yet it is the leading cause of infection in newborns.

The new trial will test the effectiveness of two types of screening compared to no screening in 80 hospitals in England and Wales. The results will inform future pregnancy screening policy in the UK.

Group B Streptococcus is a bacteria commonly found in women which causes the carrier little or no harm but it can be passed to the baby around birth.  The bacteria will not cause infection in the vast majority of babies, but 1 – 2 per cent will develop group B Strep, which causes a range of serious infections including pneumonia, meningitis and septicaemia (blood infection) and is especially dangerous to those babies born prematurely.

Group B strep infection in babies can be prevented by giving intravenous antibiotics to women during labour but there are concerns that routine testing would lead to large numbers of women being given antibiotics when they do not need them and that the longer-term effects of antibiotics on mother and baby are unknown. Widespread use of antibiotics also contributes to antimicrobial resistance in the general population.

Although routine group B strep screening is undertaken in some countries the evidence for its clinical and cost effectiveness is still uncertain.

Current UK policy is to assess whether pregnant women are likely to be carrying the bacteria using a set of criteria, and to treat accordingly. This process is not very accurate. Previous UK research has found that:

  • 65 per cent of babies who develop group B strep infections have mums who had no risk factors for carrying the bacteria
  • 70 per cent of women who do have risk factors do not actually harbour the bacteria and are therefore unnecessarily given antibiotics.

In addition, women who are found to have group B strep during pregnancy may not have the infection by the time they give birth.

The GBS3 trial aims to clarify these uncertainties by comparing usual treatment with a) using a lab culture test to check women at 35 weeks of pregnancy and b) doing a ‘bedside test’ at the start of labour.

The trial is led by Dr Kate Walker and Dr Jane Daniels, Clinical Assistant Professor of Obstetrics and Professor of Clinical Trials at the University of Nottingham School of Medicine.

For further information on this study please visit the NIHR Journals Library.