Background There are longstanding conceptual and theoretical links between political exposures and population health. Systematic reviews have demonstrated that the welfare state, political tradition, democracy and globalisation exert an important influence on population health outcomes. However, there has been no systematic analysis of the mechanisms by which these effects may operate. Therefore, taking a focus on child and maternal health outcomes, a realist re-synthesis of the dataset from an existing systematic review is presented.

Methods In order to systematically evaluate the mechanisms by which political effects on child and maternal health operate using realist methods, searches from an existing systematic review up to November 2017 were used. Ten databases were searched, and supplementary web searches and citation chasing were conducted. Included studies quantitatively investigated the link between the welfare state, political tradition, democracy or globalisation and child or maternal health outcomes in at least two countries. Following standardised duplicate screening and data extraction, initial realist theory generation took place, followed by theory adjudication to determine final theories. As realist methods were used, there was no standardised assessment of risk of bias.

Results 35,333 unique records were identified, of which 255 proceeded to full-text review, 176 to inclusion in the original systematic review, and 67 were included in this realist review on child and maternal health outcomes. Sixty-three of these studies were ecological and included data from 1950–2014. Six initial theories were generated. Following theory adjudication, three theories in revised form were supported and formed the final programme theories. These related to a more generous welfare state leading to better child and maternal health especially in developed countries through progressive social welfare policies, left-of-centre political tradition leading to lower child mortality and low birth weight especially in developed countries through greater focus on welfare measures, and increased globalisation leading to greater child and infant mortality and youth smoking rates in LMECs through greater influence of multinational corporations and neoliberal trade organisations.

Conclusion Following a realist re-synthesis of a large systematically collected dataset, three final programme theories were supported that offer an account of how the welfare state, political tradition and globalisation may exert an important effect on child and maternal health. Limitations include lack of stratification by level of development, contextual effects in interpreting fertility rates, and complexity in mapping political exposures to political parties internationally. Future realist analyses could consider other political exposures, such as governance and political capacity.