A new study shows that the use of a simple maternity innovation that measures the mother's blood pressure and pulse can be scaled nationally in Sierra Leone to aid early detection of maternal complications, but also highlights that stronger health systems are essential to save lives.
The CRADLE-5 trial, led by the Sierra Leone Ministry of Health in partnership with researchers from King's College London and iNGO Welbodi Partnership, is one of the largest maternal health implementation studies conducted in a low-income country. The trial tested the nationwide roll-out of the CRADLE Vital Signs Alert device - a pregnancy-validated blood pressure and pulse monitor with a traffic-light early warning system - across eight districts covering half of Sierra Leone.
The trial was funded by the National Institute for Health and Care Research (NIHR) and UNICEF, and the findings were published in The Lancet Obstetrics, Gynaecology, & Women's Health.
Between May 2022 and June 2023, more than 2,100 health workers were trained and 2,171 CRADLE devices distributed to 95% of government health facilities, supporting care for over 93,000 births. The study showed that CRADLE significantly improved how often and how accurately vital signs were measured, enabling earlier detection of complications such as haemorrhage, sepsis, and pre-eclampsia.
However, despite these improvements, the study found no overall reduction in maternal deaths or stillbirths - a stark reminder that technology alone cannot save lives without parallel investment in drugs, blood, ambulances, and trained staff, the authors conclude.
The trial showed that facilities without access to lifesaving drugs such as magnesium sulphate, or those staffed by workers who scored poorly in on-the-job assessments, were significantly more likely to report maternal deaths, stillbirths, emergency hysterectomies, or eclampsia. Where referral systems were functioning, CRADLE alerts were linked to significantly improved newborn survival, offering a glimpse of what is possible when early detection is matched by timely treatment.
Every number in this trial represents a mother and a baby. CRADLE empowers health workers to detect danger quickly, even when a woman feels well. But our results also show that warnings must be matched with action, and that means investment in drugs, staff, and emergency systems. Technology works when the health system works.
Dr Alexandra Ridout, Clinical Lecturer at King's and co-chief investigator of the trial
The CRADLE device is a portable, easy-to-use blood pressure and heart rate monitor that alerts users to act promptly if readings are high. The device was invented by Andrew Shennan, Professor of Obstetrics at King's, and costs less than £20.
Too many mothers are still dying from conditions we know how to detect and treat. In Sierra Leone, pre-eclampsia and other complications remain leading causes of maternal death. Innovations like CRADLE are powerful tools, but their impact depends on medicines, trained staff, and functioning referral systems. By embedding CRADLE into our national health system, training frontline workers, and aligning procurement systems, we have shown what partnership can achieve. Government leadership, together with collaboration from communities, researchers, and international partners, is turning early warnings into lifesaving action. This is how we will move from measured risk to measurable survival for our mothers and babies.
Dr Sartie Kenneh, Chief Medical Officer, Sierra Leone
I was able to survive because of CRADLE. When the nurse used the CRADLE machine, the red light flashed on. My blood pressure was so high (200/100). I felt fine but she told me I must go to the hospital. I was scared of the long journey, but also I had that red light in my mind. When I got there they said I had pre-eclampsia, and my baby must be born. We both survived, thank God. So I could go home to care for my other children. Without that machine, I would never have known anything was wrong.
A mother of three from Kono District, Sierra Leone
The trial provides evidence that innovations like the CRADLE device can be scaled nationally and embedded sustainably. The challenge for the global health community is to ensure that early warnings are matched with the resources needed to act.
