BACKGROUND: Understanding how policies lead to changes in health systems and in practice helps policymakers and researchers to intervene more successfully. Yet identifying all the possible changes that occur as a result of a new policy is challenging not only methodologically and logistically, as limited resources are available to conduct indefinite evaluations, but also theoretically, as a complete mapping and attribution of post-hoc changes requires a full understanding of the mechanisms underpinning all change. One option is to identify possible changes across a number of policy impact domains. METHODS: Using a Policy Impact Framework, we brought together data from media, documents and interviews to identify changes to midwifery policy, practice and provision, following the launch of a new global policy initiative, the State of the World's Midwifery (SoWMy 2014) report published in 2014. We used these identified impacts to develop a map of the mechanisms underpinning these changes. RESULTS: SoWMy 2014 contributed to a number of changes at national levels, including increased status of midwifery within national governments, improved curricula and training opportunities for midwives, and improved provision of and access to midwifery-led care. These contributions were attributed to SoWMy 2014 via mechanisms such as stakeholder interaction and acquisition of government support, holding national and international dissemination and training events, and a perceived global momentum around supporting midwifery provision. Policy initiatives of this kind can lead to changes in national and international policy dialogue and practice. We identify factors and mechanisms that are likely to increase the scope and scale of these changes, at contextual, national and global levels. CONCLUSIONS: Identifying changes following a policy using a policy impact framework can help researchers and policymakers understand why policies have the effect they do. This is important information for those wishing to increase the effectiveness of future policies and interventions.