ObjectiveTo quantify the economic impact of upscaling access to continuity of midwifery carer, compared with current standard maternity care, from the perspective of the public health care system. MethodsWe created a static microsimulation model based on a whole-of-population linked administrative data set containing all public hospital births in one Australian state (Queensland) between July 2017 to June 2018 (n = 37,701). This model was weighted to represent projected State-level births between July 2023 and June 2031. Woman and infant health service costs (inpatient, outpatient and emergency department) during pregnancy and birth were summed. The base model represented current standard maternity care and a counterfactual model represented two hypothetical scenarios where 50 % or 65 % of women giving birth would access continuity of midwifery carer. Costs were reported in 2021/22 AUD. ResultsThe estimated cost savings to Queensland public hospital funders per pregnancy were $336 in 2023/24 and $546 with 50 % access. With 65 % access, the cost savings were estimated to be $534 per pregnancy in 2023/24 and $839 in 2030/31. A total State-level annual cost saving of $12 million in 2023/24 and $19 million in 2030/31 was estimated with 50 % access. With 65 % access, total State-level annual cost savings were estimated to be $19 million in 2023/24 and $30 million in 2030/31. ConclusionEnabling most childbearing women in Australia to access continuity of midwifery carer would realise significant cost savings for the public health care system by reducing the rate of operative birth.