Background and Objective A postpartum haemorrhage quality improvement initiative (the Obstetric Bleeding Strategy for Wales [OBS Cymru]), including about 60,000 maternities, was adopted across Wales (2017Wales ( -2018. We performed a costconsequences analysis to inform ongoing provision and wider uptake. Methods Analysis was based on primary data from the All Wales postpartum haemorrhage database, with a UK National Health Services perspective, a time horizon from delivery until hospital discharge and no discounting. Costs were based on UK published sources with viscoelastic haemostatic assay costs provided by the OBS Cymru national team. Mean costs per eligible patient (postpartum haemorrhage > 1000 mL) were calculated for OBS Cymru, using the early implementation period as a comparator. Modelling allowed comparisons of three scenarios (two predefined and one post hoc) and implementation in different sizes of maternity unit. Results All analyses demonstrated consistent savings in blood products, critical care and haematology time, and also a reduced occurrence of massive postpartum haemorrhage (> 2500 mL). Incremental postnatal length of stay varied between scenarios, substantially impacting on total costs. Mean incremental cost of OBS Cymru, compared with standard care, across Wales was £18.41 per patient (postpartum haemorrhage > 1000 mL) or − £10.66 if the length of stay was excluded. Modelling a maternity unit of 5000 births per annum, OBS Cymru incurred an incremental cost of £9.53 per patient with postpartum haemorrhage > 1000 mL. Conclusions OBS Cymru reduces the occurrence of massive postpartum haemorrhage, need for transfusions, quantity of blood products and intensive care. In medium-to-large maternity units (>3000 maternities per annum), the OBS Cymru intervention approaches cost neutrality compared to standard care.