A realist synthesis to develop an explanatory model of how policy instruments impact child and maternal health outcomes.

BACKGROUND: Child and maternal health, a key marker of overall health system performance, is a policy priority area by the World Health Organization and the United Nations, including the Sustainable Development Goals. Previous realist work has linked child and maternal health outcomes to globalization, political tradition, and the welfare state. It is important to explore the role of other key policy-related factors. This paper presents a realist synthesis, categorising policy instruments according to the established NATO model, to develop an explanatory model of how policy instruments impact child and maternal health outcomes. METHODS: A systematic literature search was conducted to identify studies assessing the relationships between policy instruments and child and maternal health outcomes. Data were analysed using a realist framework. The first stage of the realist analysis process was to generate micro-theoretical initial programme theories for use in the theory adjudication process. Proposed theories were then adjudicated iteratively to produce a set of final programme theories. FINDINGS: From a total of 43,415 unique records, 632 records proceeded to full-text screening and 138 papers were included in the review. Evidence from 132 studies was available to address this research question. Studies were published from 1995 to 2021; 76% assessed a single country, and 81% analysed data at the ecological level. Eighty-eight initial candidate programme theories were generated. Following theory adjudication, five final programme theories were supported. According to the NATO model, these were related to treasure, organisation, authority-treasure, and treasure-organisation instrument types. CONCLUSIONS: This paper presents a realist synthesis to develop an explanatory model of how policy instruments impact child and maternal health outcomes from a large, systematically identified international body of evidence. Five final programme theories were supported, showing how policy instruments play an important yet context-dependent role in influencing child and maternal health outcomes.