Introduction Early recognition of haemodynamic instability following PPH is necessary to instigate interventions to prevent maternal morbidity and mortality. Conventional markers of haemodynamic compromise are relatively insensitive.

Objectives To evaluate SI, the ratio of heart rate (HR) to systolic blood pressure (SBP), as a predictor of adverse clinical outcome following PPH, compared to SBP, diastolic blood pressure (DBP), HR, mean arterial pressure (MAP) and pulse pressure (PP).

Methods A retrospective study of women with PPH of 1500ml or more at a large tertiary referral centre over a one-year period (n = 233). SBP, DBP, and HR were collected within the first hour following PPH recognition and SI, MAP, and PP were calculated. Adverse outcomes included haemoglobin level <7 g/dL, blood transfusion ≥4 units and admission to ICU.

Results Area under the ROC curve of each predictor (95% confidence interval).

Conclusion SI was superior to standard vital signs and may be a useful predictor of adverse clinical outcome in women with PPH. SI could easily be incorporated into early warning algorithms in postpartum care.