Using the behaviour change wheel to explore infant feeding peer support provision; insights from a North West UK evaluation.

Background: Breastfeeding peer support is advocated in national and international guidelines, but the evidence base is mixed. In the UK, breastfeeding peer support was found to be ineffective in randomised controlled trials, while women report positive impacts on breastfeeding experiences in qualitative studies. A key criticism levied against breastfeeding peer support is the lack of theory underpinning intervention design. Here we use the Behaviour Change Wheel to structure the analysis of evaluation data from an infant feeding peer support service in one area in North West England. We aimed to provide theoretically informed insights into how peer support can be operationalised to influence women's breastfeeding experiences. Methods: A 2 year mixed-methods evaluation (2014-2016) comprised surveys and interviews (individual or group) with peer supporters, health and community professionals, project leads and women, and routinely collected infant feeding data. We used the three layers (policies, intervention functions and behaviour-related components) of the Behaviour Change Wheel to structure and interpret the data. Results: Overall data comprised 23 interviews ( Conclusion: While gaps and areas for development were highlighted, the service enhanced women's capabilities, motivations and opportunities for breastfeeding. These theoretically informed insights into an organic and responsive peer support service help build the evidence base for breastfeeding peer support and to identify positive delivery features for future testing.