Predicting postpartum haemorrhage: A systematic review of prognostic models

BACKGROUND: Postpartum haemorrhage (PPH) remains a leading cause of maternal mortality and morbidity worldwide, and the rate is increasing. Using a reliable predictive model could identify those at risk, support management and treatment, and improve maternal outcomes. AIMS: To systematically identify and appraise existing prognostic models for PPH and ascertain suitability for clinical use. MATERIALS AND METHODS: MEDLINE, CINAHL, Embase, and the Cochrane Library were searched using combinations of terms and synonyms, including ‘postpartum haemorrhage’, ‘prognostic model’, and ‘risk factors’. Observational or experimental studies describing a prognostic model for risk of PPH, published in English, were included. The Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies checklist informed data extraction and the Prediction Model Risk of Bias Assessment Tool guided analysis. RESULTS: Sixteen studies met the inclusion criteria after screening 1612 records. All studies were hospital settings from eight different countries. Models were developed for women who experienced vaginal birth (n = 7), caesarean birth (n = 2), any type of birth (n = 2), hypertensive disorders (n = 1) and those with placental abnormalities (n = 4). All studies were at high risk of bias due to use of inappropriate analysis methods or omission of important statistical considerations or suboptimal validation. CONCLUSIONS: No existing prognostic models for PPH are ready for clinical application. Future research is needed to externally validate existing models and potentially develop a new model that is reliable and applicable to clinical practice.