SIPHRE Shock Index in Pregnancy: Haemorrhage Risk Evaluation. Shock index as a predictor of adverse outcome in maternal haemorrhage 800 women die in pregnancy and childbirth each day, 99% of these occur in low-middle income countries (LMICs). Haemorrhage can cause death within a few hours if not recognised and managed quickly and is the leading cause of maternal death worldwide. Early detection and effective management rely on monitoring of vital signs , including heart rate and blood pressure. We have effective management to prevent death from bleeding, but most deaths or severe morbidities occur because of delayed or substandard care in the diagnosis and management; in many low- middle income countries (LMIC) vital signs are not measured due to lack of staff/ equipment or poorly functioning devices, leaving the recognition of compromised patients to crude visual estimation of blood loss alone or late signs such as collapse.  Our project is a validation study of a vital signs ratio called shock index (SI)- a simple calculation using heart rate divided by blood pressure. Our previous work on SI in pregnancy and haemorrhage suggests it is a superior way of recognising compromised patients. Since SI is simple to measure and easy to apply to daily practice, we hope to demonstrate it is an effective tool for early recognition of bleeding patients at risk of poor outcome (major surgery, major blood loss or death) with the aim to reduce maternal mortality and morbidity in LMIC.   The CRADLE VSA (CVSA) device accurately measures blood pressure and heart rate, displaying the results on a screen. It shows a red/amber/green traffic light warning system consistent with shock index thresholds to alert users to the patient's risk compromise, thus allowing prompt referral or escalation of management by even untrained health workers. The CVSA device has been designed and extensively validated by our team over 15 years to become the cheapest and most accurate device to measure BP at the high and low range we see in pregnancy. It is recognised as one of the top thirty high impact innovations in global health. It has been developed for use in LMIC being light, inexpensive, robust and easy to use. The use of the CVSA was extensively researched in the CRADLE 3 trial. In country data from Sierra Leone (SL) showed its implementation reduced maternal death rate by 60% (RR 0.37 CI 0.25 to 0.550). Following its success, the Department of Health in Sierra Leone are now rolling out the CRADLE VSA device nationwide, supported by DIFD, WHO, UNICEF and JICA.  We propose a prospective validation study of shock index in Sierra Leone, where adverse outcomes are so prevalent, in order to obtain large data to support SI as a tool for earlier recognition of compromise in bleeding mothers. SL has the world's highest mortality rate (1,165 deaths per 100,000 live births. In the UK this is 9 per 100,000). Data including first and worst vital signs and clinical outcomes will be collected on all pregnant/postpartum women who suffer with haemorrhage (blood loss over 500mls). The performance of shock index to predict adverse clinical outcomes will be evaluated and compared to existing vital signs scores.   A standardised early warning system for recognition of compromised patients does not exist for use in LMIC. Following validation on SI we propose a trial to evaluate the effect of SI in triage and management of bleeding patients in LIC. It is anticipated that a care bundle that incorporates SI as a triage/referral criteria will improve care. Since avoidable maternal deaths and near-misses are often related to delays in recognition of hemodynamic compromise this simple automated early warning system could be used in LIC worldwide. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.