A simple device that measures a mother’s blood pressure and pulse is showing promise in improving maternal health care in Sierra Leone, one of the world’s most dangerous places to give birth.
The device, called CRADLE Vital Signs Alert, helps health workers detect life-threatening complications early.
However, a major new study shows that while the technology works well, stronger health systems are still needed to turn early warnings into lives saved.
The CRADLE-5 trial, led by the Sierra Leone Ministry of Health with researchers from King’s College London and the charity Welbodi Partnership, is one of the largest studies ever conducted in a low-income country to test a maternal health innovation.
The results, published in The Lancet Obstetrics, Gynaecology & Women’s Health, show that the device can be used successfully across an entire nation.
Between May 2022 and June 2023, more than 2,100 health workers were trained and over 2,100 CRADLE devices were distributed to nearly every government health facility—supporting care for more than 93,000 births. The device uses a simple traffic-light system: green means normal, amber signals concern, and red warns of danger. It enabled earlier detection of serious conditions such as hemorrhage, sepsis, and pre-eclampsia, one of the leading causes of maternal death.
Despite these gains, the study found no overall drop in maternal deaths or stillbirths. Researchers say this highlights a critical point: technology alone cannot save lives without access to medicines, blood supplies, trained staff, and working ambulances. In facilities that lacked basic drugs like magnesium sulfate, or where staff had limited training, deaths and complications remained higher. But in areas with good referral systems, CRADLE alerts were linked to improved newborn survival rates.
“Every number in this trial represents a mother and a baby,” said Dr. Alexandra Ridout from King’s College London, co-lead of the study. “CRADLE empowers health workers to detect danger quickly, but detection must be followed by action—by treatment, transport, and skilled care.”
The CRADLE device, invented by Professor Andrew Shennan at King’s College London, costs less than £20 and can be used even in rural clinics with limited resources.
One mother from Kono District shared how it saved her life: “The nurse used the CRADLE machine, and the red light flashed. I felt fine, but she told me to go to the hospital. They said I had pre-eclampsia and my baby had to be born. We both survived—without that machine, I would never have known.”
The trial proves that low-cost, easy-to-use technology can be rolled out nationally. The next challenge, experts say, is ensuring that early warnings from devices like CRADLE are matched with the resources needed to save mothers and babies everywhere.
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Source: King’s College London.
