Background of the study
Postpartum haemorrhage, defined historically as blood loss of 500 mL or more within 24 hours after childbirth, is a leading contributor to global maternal death and severe morbidity. However, the conventional threshold may miss many women who are already at risk of serious complications.
To address this gap, researchers pooled and re-analysed individual patient datasets from 12 eligible studies, representing 312,151 women worldwide. They assessed the ability of five clinical markers - measured blood loss, pulse rate, systolic and diastolic blood pressure, and the shock index (a ratio of heart rate to systolic blood pressure) - to predict a composite outcome of maternal mortality or severe morbidity, including blood transfusion, surgical interventions, or intensive care admission.
Key Findings
- At the conventional threshold of 500 mL, measured blood loss had reasonable predictive accuracy, with moderate sensitivity and high specificity for severe outcomes.
- Lowering the measured blood loss threshold to 300 mL improved the sensitivity of detection - meaning more women at risk could be identified earlier (although specificity was reduced.)
- The strongest predictive performance came from a combined rule that used either modest blood loss (300–450 mL) plus any abnormal vital sign (e.g., elevated pulse rate, low blood pressure, or elevated shock index) or blood loss of 500 mL or more. This combined approach yielded high sensitivity (~87%) and very good specificity (~67–76%).
Why This Matters
These results challenge reliance on a single blood-loss threshold alone. By incorporating both measured blood loss below the traditional threshold and simple clinical signs of haemodynamic instability, clinicians could identify women at risk earlier, enabling prompt lifesaving treatment interventions. The findings are especially relevant in low-resource settings, where delays in recognising severe PPH contribute disproportionately to maternal deaths. Integrating these combined criteria into clinical practice could help refine global guidelines on PPH diagnosis and management.
Explainer video
Prof Arri Coomarasamy explains more on the video in accessible terms, highlighting practical implications for clinicians and maternal health policymakers.
Publication
Prognostic accuracy of clinical markers of postpartum bleeding in predicting maternal mortality or severe morbidity: a WHO individual participant data meta-analysis
Further resources
- Early Diagnosis Saves Lives: New Study Highlights Critical Window for Postpartum Haemorrhage Care
- E-MOTIVE: First Response Treatment for Postpartum Haemorrhage (PPH).
For media enquiries
Rob Phillips, Communications Manager at the Nuffield Department of Women’s & Reproductive Health, University of Oxford, rob.phillips@wrh.ox.ac.uk