Introduction This report, the twelfth MBRRACE-UK annual report of the Confidential Enquiries into Maternal Deaths and Morbidity, includes surveillance data on 611 women who died during or up to one year after pregnancy between 2021 and 2023 in the UK. In addition, it includes confidential enquiries into the care of women who died between 2021 and 2023 in the UK and Ireland from hypertensive disorders of pregnancy, cardiac disease, mental health-related causes, homicides and accidents. The report also includes a Morbidity Confidential Enquiry into the care of women living in the most deprived areas of the UK. These women were selected from the MBRRACE-UK database of perinatal deaths for 2023. To compare the care these women received to a control population, women living in the least deprived areas were also sampled from the database of perinatal deaths and from national birth registers and matched based on region, ethnic group and age range within five years. The care of 33 women living in the most or least deprived areas was reviewed in depth for the Morbidity Confidential Enquiry. Seventeen women who were identified as having multiple disadvantages, including but not limited to deprivation, are included in Chapter 5: Lessons for the care of women with multiple disadvantages. Lessons from the care of other women included in the morbidity enquiry are discussed in other chapters of the report.

This report can be read as a single document; each chapter is also designed to be read as a standalone report as, although the whole report is relevant to maternity staff, service providers and policy-makers, there are specific clinicians and service providers for whom only specific chapters are pertinent. There are seven different chapters covering the following topics: 1. Introduction and methodology 2. Maternal mortality surveillance and epidemiology 3. Hypertensive disorders of pregnancy 4. Cardiac disease 5. Multiple disadvantages (including accidental deaths and homicides as well as women reviewed as part of the morbidity enquiry) 6. Mental health and 7. Pathology.