1920_251: The clinical and cost-effectiveness of testing for Group B Streptococcus in pregnancy: a cluster randomised trial with economic and acceptability evaluations (GBS3)
Source: gov.uk (2025-08-04)

The aim of this project is to find out if offering testing for the bacteria Group B Streptococcus to all pregnant women, will reduce the occurrence of early-onset infection (sepsis) in newborn babies, when compared to the current standard care offered to parents in the UK.

About the project

What the project aims to do

The aim of this project is to find out if offering testing for the bacteria Group B Streptococcus to all pregnant women, will reduce the occurrence of early-onset infection (sepsis) in newborn babies, when compared to the current standard care offered to parents in the UK.

Currently women whose babies are at higher risk of developing the infection, based on maternal risk factors, are given antibiotics in labour to prevent and reduce the occurrence of infection in their babies.

This study will assess 2 methods of routine testing which are available, compared to the current policy of giving antibiotics based on maternal risk factors. 71 maternity units will take part in this study and will use one of the 3 treatments. The 2 methods of routine testing use vaginal-rectal swabs, either taken at 35 to 37 weeks of pregnancy and used in a test called enriched culture medium (ECM), or taken in labour and used in a rapid test. An economic analysis will also be performed with the aim to identify, measure and value the costs and consequences of these testing strategies for GBS in pregnancy or labour.

Why this project is important

The current UK standard care for pregnant women, based on ‘risk factor screening’ is believed to be imperfect. Some babies are missed and develop GBS and some women with risk factors do not carry GBS and therefore receive antibiotics unnecessarily. One possible solution is to test all women (universal screening) during pregnancy to determine if they carry GBS. However, in 2017, the UK National Screening Committee (NSC) concluded that they could not recommend universal screening for GBS in the UK due to lack of evidence in efficacy and costs. The NIHR therefore called for the GBS3 trial be carried out to gather evidence on whether a universal screening program is both effective in reducing the newborn infection and if the costs are acceptable.

Who the data is about

New-borns and mothers in the GBS3 trial.

How the data will be used

Due to the very large number of participants (320,000 women) in the trial, the results will be gathered from data that is routinely collected by the NHS. UKHSA data will be used to help identify all relevant confirmed cases of infection in babies that are reported during the trial. This will help the trial team to determine if universal screening reduces the number of cases compared to the current risk factor approach. As the study will also look at cases of maternal sepsis during and after delivery, positive tests for sepsis for women prior and after delivery will also be used.

The UKHSA data will be linked to other national datasets obtained from different data providers, including NHS England, Clevermed, PicaNET, and Imperial College. This data will include information on women characteristics (age, ethnicity), what happened during labour, baby’s characteristics such as weight or gestational age, if a baby needed special care when they were born, or if a woman or a baby died. This will also enable identification of the type of tests women received and describe the different groups under analysis. The main aim is to compare the number of cases of sepsis in the 3 treatment groups to identify the best treatment to reduce sepsis in newborn. The economic analysis will also look if these tests incur reasonable costs for the NHS.

All the data will be sent to Trusted Research Environment (TRE) located at University of Dundee. Minimally identifiable data (NHS number, date of birth and full postcode) will be used to link all the relevant datasets before being removed to pseudonymise the final dataset used for the analysis. This will be done remotely by a data manager located in Nottingham. Two researchers teams from Nottingham and Oxford will access the pseudonymised data remotely and will perform the study without taking the data outside the TRE.

When the study is finished all the data obtained from each data provider will be safely destroyed. Only the final dataset for analysis will be kept in pseudonymised format. The personal identifiers (such as NHS number) will be safely kept in a separate location. This data will be retained for 7 years as per University of Nottingham policy and if further research will be conducted in the future using this data, new approvals will be obtained.

If a woman does not want to have their data shared with the researcher’s team, they can opt-out using the national data out-out service.

How often data is needed

One off release.

How this project will benefit public health and the public

The results of this trial will help the UK National Screening Committee decide whether or not routine testing for GBS in pregnant women should be used in the whole UK to help reduce the number of GBS infection in babies, which can lead to long-term health problems or death. It may also help to reduce the use of antibiotics where they are not needed. This is also an important benefit as antibiotics may cause complications for the mother (severe allergic reaction, complication during delivery) or baby (effects on the development of their internal organs), may have also long term complications for the mother or baby and an excessive use of antibiotics (when not needed) may decrease their success against bacteria both for the individual and the rest of the population.

Planned project outputs and communication
- peer-reviewed scientific journals
- internal report (publication not intended)
- conference presentation
- website
- press release
Lawful processing of personal and special category personal data

Under the UK General Data Protection Regulation (UK GDPR), the data required for this project is classified as special category personal data. This means that, in order for the processing of this data to be lawful, there must be both a lawful basis for processing under Article 6 and a separate condition for processing under Article 9 of the UK GDPR.

Legal basis for using personal data (Article 6)

UK GDPR Article 6(e): processing is necessary for the performance of a task carried out in the public interest or in the exercise of official authority vested in the Controller

Legal basis for using special category personal data (Article 9)

UK GDPR Article 9(2)(j): processing is necessary for archiving purposes in the public interest, scientific or historical research purposes or statistical purposes in accordance with Article 89(1) based on Union or Member State law which shall be proportionate to the aim pursued, respect the essence of the right to data protection and provide for suitable and specific measures to safeguard the fundamental rights and the interests of the data subject.

Common law duty of confidentiality

The data needed for this project includes Confidential Patient Information — meaning data that can both identify an individual and relate to their health or care, shared in a context where confidentiality is expected and protected.

Confidential Patient Information is subject to a strict duty of confidentiality. It can only be used with the patient’s explicit consent or under specific legal provisions that permit its use — for example, for medical research or public health purposes.

How is the duty of confidentiality set aside

Regulation 5, Health Service (Control of Patient Information) Regulations 2002

National Data Opt-Out

Opt-out preferences will be applied.

Digital Object Identifier:

Not assigned to this release.

Organisatons Research Organisation Registry (ROR) ID:

ROR ID (https://ror.org/01ee9ar58)