National scale-up of maternal vital signs technology improves detection in Sierra Leone but shows no reduction in deaths, major trial finds

A major national trial in Sierra Leone has found that rolling out a low-cost maternal vital signs monitoring system across government health facilities significantly improved the detection and recording of maternal complications, but did not reduce deaths or severe adverse outcomes.

The findings come from the CRADLE-5 trial, a large stepped-wedge cluster randomised study published in The Lancet, which evaluated whether scaling up the CRADLE Vital Signs Alert (VSA) device could improve maternal and newborn outcomes when integrated into routine health services.

High maternal mortality despite global progress

Sierra Leone continues to have one of the highest maternal mortality ratios in the world, estimated at 443 deaths per 100,000 live births in 2020, despite substantial progress over the past two decades. Most maternal deaths are caused by preventable complications including haemorrhage, hypertension and sepsis.

However, the study notes that up to 20% of facilities in Sierra Leone still lack functioning blood pressure equipment, limiting early detection of deterioration in pregnant women - an essential step in preventing severe outcomes.

What the CRADLE intervention is

The CRADLE intervention combines a handheld, pregnancy-validated blood pressure and pulse device with a “traffic-light” early warning system that flags abnormal readings linked to conditions such as pre-eclampsia, haemorrhage and sepsis.

The system is designed for low-resource settings and is supported by a structured training programme for frontline health workers, including cascade training delivered by locally trained “CRADLE champions”.

The aim is simple: improve early recognition of deterioration so women can be referred and treated more quickly.

Study design and scale

The CRADLE-5 study was a pragmatic, type 2 hybrid implementation–effectiveness stepped-wedge cluster randomised trial conducted across eight rural districts in Sierra Leone between May 2022 and June 2023.

• 93,811 deliveries were included

• 674 government health facilities participated

• 2,135 health workers were trained

• 2,171 devices were distributed

  
  

Each district transitioned from standard care to the intervention in a randomised sequence, allowing researchers to compare outcomes before and after implementation.

Improved monitoring, better detection - but no change in mortality

The intervention was successfully implemented at scale and led to clear improvements in clinical practice:

• Blood pressure monitoring increased significantly (IRR 1.38, 95% CI 1.07–1.77)

• Measurement accuracy improved sharply, with “digit preference” (recording rounded values) falling from 32.8% to 8.7%

• Training coverage reached 95% of government facilities

  
  

Despite these improvements, there was no significant reduction in the primary composite outcome, which included eclampsia, emergency hysterectomy, maternal death or stillbirth.

Maternal deaths, stillbirths and severe complications remained statistically unchanged between pre- and post-intervention periods.

System constraints limited clinical impact

Researchers concluded that while detection improved, health system limitations prevented this from translating into better outcomes.

Major barriers included:

• Frequent stockouts of essential medicines such as magnesium sulphate and antibiotics

• Limited availability of emergency obstetric care

• Low rates of caesarean section (around 1%) and hysterectomy (0.1%)

• Staff shortages, with most deliveries conducted by low- or unskilled workers

• Weak ambulance and referral systems in several districts

• Infrastructure gaps, including unreliable electricity supply in 15% of facilities

  
  

The authors describe these constraints as key reasons why improved monitoring did not lead to reduced mortality.

A potential signal in neonatal outcomes

Although the main outcomes were unchanged, a post-hoc analysis suggested a possible reduction in neonatal deaths among women who were referred after a CRADLE alert when the system was acted upon effectively.

Among referred women, neonatal deaths decreased from 5.8% to 2.5% (RR 0.08, 95% CI 0.02–0.29), although researchers caution that this was an exploratory finding and should be interpreted carefully.

What the findings mean

The authors conclude that the CRADLE system is highly feasible to implement at national scale and improves clinical detection and referral signals, but cannot reduce mortality in isolation.

The study highlights a key principle in global maternal health: technology alone is not sufficient without a functioning health system capable of responding to alerts.

In particular, improvements in outcomes depend on:

• Availability of essential drugs

• Skilled staff and surgical capacity

• Effective referral and transport systems

• Reliable infrastructure and supply chains

  
  

Wider implications

The trial provides one of the largest real-world evaluations of a maternal early warning system in a low-income country.

It suggests that pregnancy-specific vital signs tools can be successfully embedded into national health systems, but must be paired with broader investment in emergency obstetric and newborn care if they are to reduce mortality.

The authors argue that future maternal health strategies should focus on combining early detection technologies with system strengthening, rather than implementing either in isolation.

Conclusion

The CRADLE-5 trial shows that scaling up maternal vital signs monitoring across an entire national health system is achievable and improves clinical practice at scale. However, without the supporting infrastructure to act on warnings, the impact on maternal and newborn survival remains limited.

The findings reinforce a central message in global maternal health research: saving lives depends not only on better tools, but on stronger systems.

Sources

• The Lancet — CRADLE-5 trial: national scale-up of CRADLE Vital Signs Alert intervention in Sierra Leone (2025–2026)

• UN Maternal Mortality Estimates (Sierra Leone, 2020)

• WHO maternal health guidance and emergency obstetric care standards

• Sierra Leone Ministry of Health service delivery data (as reported in trial)