BackgroundDespite the significant variability in the role and integration of midwifery across provincial and territorial health systems, there has been limited scholarly inquiry into whether, how and under what conditions midwifery has been assigned roles and integrated into Canada’s health systems.MethodsWe use Yin’s (2014) embedded single-case study design, which allows for an in-depth exploration to qualitatively assess how, since the regulation of midwives in 1994, the Ontario health system has assigned roles to and integrated midwives as a service delivery option. Kingdon’s agenda setting and 3i + E theoretical frameworks are used to analyze two recent key policy directions (decision to fund freestanding midwifery-led birth centres and the Patients First primary care reform) that presented opportunities for the integration of midwives into the health system. Data were collected from key informant interviews and documents.ResultsNineteen key informant interviews were conducted, and 50 documents were reviewed in addition to field notes taken during the interviews. Our findings suggest that while midwifery was created as a self-regulated profession in 1994, health-system transformation initiatives have restricted the profession’s integration into Ontario’s health system. The policy legacies of how past decisions influence the decisions possible today have the most explanatory power to understand why midwives have had limited integration into interprofessional maternity care. The most important policy legacies to emerge from the analyses were related to payment mechanisms. In the medical model, payment mechanisms privilege physician-provided and hospital-based services, while payment mechanisms in the midwifery model have imposed unintended restrictions on the profession’s ability to practice in interprofessional environments.ConclusionsThis is the first study to explain why midwives have not been fully integrated into the Ontario health system, as well as the limitations placed on their roles and scope of practice. The study also builds a theoretical understanding of the integration process of healthcare professions within health systems and how policy legacies shape service delivery options.