New Maternity Early Warning Score to be implemented across the NHS

Researchers in Oxford have developed a new maternity early warning score that is derived from patient data.

The new system, which is being rolled out across the English NHS, will help healthcare providers identify and respond to signs of deterioration in pregnant women.

Maternity Early Warning Scores (MEWS) are widely used throughout hospitals in the UK to highlight when additional care is needed to protect the health of the expectant mother and baby. 

The majority of MEWS have been developed by clinical consensus and their implementation varies widely across the country. However, a research team from the University of Oxford recognised the need to provide solid observational evidence for a standardised national MEWS, leading to a collaboration with the National Maternity and Neonatal Programme.

The research, published in BMJ Medicine, involved analysing vital sign measurements from over 1,000 pregnant women who took part in the three-centre 4P (Pregnancy Physiology Pattern Prediction) study.

Led by Professor Peter Watkinson, 4P was funded by the National Institute for Health and Care Research (NIHR) Oxford Biomedical Research Centre (BRC). 

The researchers used statistical modelling to determine appropriate thresholds for each vital sign - including blood pressure, heart rate, respiratory rate, temperature, and oxygen levels. These thresholds were then used to assign numerical scores, with higher scores indicating more concerning vital sign measurements.

Tony Kelly and Hannah Rutter at NHS England’s National Maternity and Neonatal Programme led a design group of representative stakeholders to use this observational evidence to support the creation of the English national Maternal Early Warning Score.

Together they conducted a Delphi consensus exercise with more than 30 experts to establish agreed-upon clinical responses to elevated MEWS scores. This ensures that the new National MEWS not only identifies potential problems, but also provides clear guidance on the appropriate escalation of care.

One key advantage of the new National MEWS is that it triggers unnecessary alerts less frequently in healthy pregnant women compared to existing MEWS systems used in the UK. This should help reduce alarm fatigue and ensure the tool is used effectively.

Professor Watkinson, Professor of Intensive Care Medicine at the Nuffield Department of Clinical Neurosciences and a consultant at Oxford University Hospitals (OUH) NHS Foundation Trust, said: "The main goal when we embarked on the Oxford BRC-funded 4P study was to develop a standardised, evidence-based early warning system that could benefit women during and shortly after pregnancy across the country. We are delighted that, by working with maternity experts at NHS England, we are now on the verge of achieving this.

"Because our new system uses normal ranges derived from the results of a large prospective study, it should considerably reduce alerts in healthy women compared with existing MEWS systems. The consistent evidence-based score and expert-ratified escalation pathways mean that this MEWS could be replicated in other similar healthcare systems."

Stephen Gerry, Senior Medical Statistician at the University of Oxford's Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), added: "Our goal was to create a MEWS that is intuitive and familiar to clinicians, while grounding it in research evidence. It was designed through a rigorous process involving midwives, doctors and other experts. By using prospectively collected vital sign data we were able to develop thresholds that reflect normal physiological values during pregnancy, rather than relying on subjective expert opinion."

Tony Kelly and Hannah Rutter at National Maternity and Neonatal Programme, NHS England commented: "The new National Maternity Early Warning Score tool will allow us to improve the quality and consistency in the identification of episodes of deterioration in the pregnant population. This is the first national tool for England and the first based on population data.

"The paper version of the tool has already been implemented in 16 units across the country and we are starting implementation in the remaining paper-based organisations over the next few months. National digital specifications are nearly complete and then we will move into a phase of digital implementation. The overall aim is that, through early identification, escalation and response the National MEWS tool will be used to assess and manage deterioration of all pregnant women and people in every organisation across England by March 2026."

The programme of work will continue as part of a new NIHR-funded project, which aims to develop and test a more sophisticated MEWS incorporating more information, such as blood tests and characteristics of the mother.

Minister for Women's Health Strategy, Maria Caulfield said: "This research is crucial to supporting our aim to provide safe and compassionate care to all women in maternity services. The new system will result in fewer false alarms and provide better care for mums and mums-to-be.

"This supports our ongoing work to improve maternity care, backed by an additional £186 million a year to improve maternity and neonatal care, on top of a further £35 million to further improve safety."

Professor Helen McShane, Director of the NIHR Oxford BRC said: "It is wonderful to see that our BRC's support for the 4P study has resulted in a system that will deliver more consistent and targeted help during and just after pregnancy. This is the essence of what we do - taking scientific advances and translating it into improvements for NHS patients. I look forward to seeing this MEWS rolled out across the NHS in England."

Professor Marian Knight, NIHR Scientific Director for Research Infrastructure, noted "This research shows the huge value of NIHR-funded infrastructures such as the Biomedical Research Centres. Conducting the early phases of this work to determine the normal ranges of measurements for pregnant women within the Oxford BRC has then allowed us to work with colleagues in NHS England to develop a system to give us better warning of when pregnant women are becoming sick and roll it out across the NHS. Further NIHR funded work will then allow us to take this further and develop a tool which will specifically help to tackle maternity inequalities."

Andrew Brent, Chief Medical Officer at OUH, said: "There is a need for an evidence-based early warning score during and shortly after pregnancy, and I am delighted that this collaborative project led by Oxford has delivered such a tool that will now be rolled out nationally. By balancing the need to identify patients at risk of deterioration while minimising 'false alerts', the new national MEWS will help clinicians to recognise and prioritise the sickest patients, allowing early intervention to further improve patient safety."

Pictured: doctor measures pregnant woman's blood pressure (Shutterstock)