2 July 2020
Pre-eclampsia affects up to 6% of pregnancies in the UK and can cause serious problems for mothers and babies – but diagnosis is a challenge because the exact cause is unknown, so women don’t always get the right treatment at the right time.
The National Institute for Health and Care Excellence (NICE) tells professionals to treat women as vulnerable to pre-eclampsia if they have 1 major risk factor or 2 moderate risk factors, but research evidence suggests this approach is too simplistic for such a complex condition. Without a more precise system, doctors have to err on the side of caution, so that can lead to unnecessary treatment which may involve stressful hospital stays and even inducing premature birth.
Studying pre-eclampsia tests and treatments
A large study of more than 17,000 pregnancies across 7 NHS hospitals compared the standard NICE pre-eclampsia screening process with an algorithm developed by the Fetal Medical Foundation that looks at various combinations of complex risk factors, from maternal blood pressure and fetal blood flow to levels of placental growth factor and pregnancy associated plasma protein-a.
Researchers found that all algorithm combinations were better at detecting pre-eclampsia than the methods advised by NICE, and the most effective version of the algorithm had an 82% success rate compared with 41% for the standard screening. Aspirin is recommended to prevent pre-eclampsia, but the study also highlighted that clinicians were less likely to prescribe this treatment when following the NICE process than when using the algorithm – maybe because they were aware of the limitations of the standard screening.
A separate clinical trial showed giving aspirin to women with high-risk pregnancies reduced rates of pre-term (before 37 weeks) and early (before 34 weeks) pre-eclampsia by 62% and 82% respectively. In women who still went on to develop pre-eclampsia, aspirin delayed the onset of the condition by 2 weeks, which can reduce hospitalisation and the need to deliver the baby very prematurely.
Our new approach to pre-eclampsia care
Specialists at St George’s University Hospital NHS FT, led by consultant obstetrician Professor Basky Thilaganathan who runs Tommy’s National Centre for Maternity Improvement, looked at data from more than 12,500 women who came to the hospital for pre-eclampsia screening in early pregnancy (before 14 weeks) between 2017 and 2019.
Women were split into two groups, carefully balanced to avoid differences in other characteristics that could affect pre-eclampsia risk, and one had standard NICE screening while the other used the algorithm. Basky’s team then followed the algorithm with a special care pathway, giving aspirin and extra growth scans to those at risk of pre-eclampsia and planning to induce labour at 40 weeks.
Findings published today in BJOG: An International Journal of Obstetrics and Gynaecology show this combination of algorithm screening and special care pathway led to an overall 23% reduction in pre-eclampsia rates over the course of the study, and an 80% reduction in women presenting with preterm pre-eclampsia (the more clinically severe form of the condition).
Screening with the algorithm halved the number of women deemed high-risk (8.2% compared to 16.1% with NICE) and led to 6 times more aspirin prescriptions (99% versus 28.9%) – probably because the lower numbers made the workload more manageable for clinical staff. The algorithm also showed significantly higher sensitivity and specificity than NICE screening.
Putting this research into practice
As part of our mission to make the UK the safest place in the world to give birth, we need the NHS to be able to access and implement our researchers’ findings, so that all maternity care providers and expectant parents can reap the benefits.
Study author and Tommy’s National Centre for Maternity Improvement director Professor Basky Thilaganathan, explained: “This screening programme is feasible in an NHS setting and has resulted in a significant reduction of the earliest and most severe form of pre-eclampsia – so this study clearly demonstrates that the continued use of the current maternal risk-factor based pre-eclampsia screening programme in routine healthcare settings must be re-evaluated.”
Tommy’s chief executive Jane Brewin commented: “Putting this new research into practice has the potential to completely transform maternity care, benefitting doctors and patients alike by finding out who’s really at risk and personally tailoring their care so that precious NHS resources can be focused on those most in need.
“Previous trials have proven the benefits of these tests and treatments, and now the team at St George’s has applied that science with such encouraging results, there’s more than enough evidence to say that national guidelines on pre-eclampsia should be reconsidered so that healthcare professionals can be empowered to provide the best support in the easiest way.
“These findings are just the beginning; our National Centre for Maternity Improvement will continue working to develop this pioneering tool, and other lifesaving interventions, which we aim to equip the NHS with so that everyone can get the right care in the right place at the right time.”
More about this ongoing work
Tommy's National Centre for Maternity Improvement is our newest research venture, opened in September 2019, as part of an alliance with the Royal College of Obstetricians and Gynaecologists and Royal College of Midwives supporting Government objectives to reduce stillbirth and premature birth.
The Centre brings together world-renowned clinical researchers from Bristol, Sheffield and London, as well as working closely with the NHS to ensure the findings of their studies are translated to real public healthcare settings where they can benefit patients and professionals alike.
Under the leadership of Professor Basky Thilaganathan, our researchers are creating a digital tool to improve the quality of maternity care across the NHS and help healthcare professionals tailor their support to the unique needs of each individual pregnancy. We're also working to create an ideal model of maternity care that can be scaled up nationwide, in order to reduce the current inequalities between different providers and regions.