Participatory methodologies have become imperative when developing health promotion programmes. However, the concrete adoption of co-creation and its implications for intervention development are less reported. This article aims to convey how fidelity and adaptation were balanced in a structured intervention design by co-creating intervention components with various stakeholders. The intervention was part of the Face-it programme, which was initiated to prevent diabetes and increase the quality of life in women with prior diabetes during pregnancy by supporting the entire family’s health practices. We relied on participatory methods, e.g. workshops using design games, role play and family interviews, as well as ethnographic fieldwork. Stakeholders comprised women with prior gestational diabetes mellitus and their families as intervention receivers and healthcare professionals, e.g. obstetricians, midwives and health visitors as potential intervention deliverers to shape intervention content. We used Bammer’s stakeholder participation spectrum in research to describe how different stakeholders were engaged and with what implications for the intervention components. This article shows how an iterative co-creation process was (i) achieved through diverse involvement practices across stakeholder groups; and (ii) upheld both premises of the structured design (fidelity) and flexibility (adaptation) in developing intervention content and delivery. When adopting co-creation as a strategy for intervention development, we recommend using various engagement practices according to the role of stakeholders in the intervention and available resources to create ownership and sustainable intervention content.

This article argues that by involving stakeholders in intervention development differently according to their available resources, and intervention roles, we can optimize co-creation processes and thus increase the likelihood of intervention sustainability. We describe how co-creation was pursued by involving multiple stakeholders comprising: families where the mother previously had a pregnancy-related diabetes (target group); healthcare professionals working with women with diabetes in pregnancy, including health visitors (intervention deliverers). We engaged in co-creation through workshops using design games, in-depth interviews and ethnographic fieldwork to understand families’ experiences with gestational diabetes and how these experiences can be used to facilitate health practices after birth. Also, we negotiated intervention content and delivery with health visitors, which optimized feedback processes to adapt intervention content and strengthened the health visitors’ ownership towards delivering the intervention as intended. By using Bammer’s stakeholder-participation-spectrum in research, we show how we tailored co-creation to the target group, intervention deliverers and other key stakeholders in intervention development. Further, we suggest collaborating and empowering intervention deliverers as part of the solution in balancing the underlying premises of a structured design with the social dynamics learned from the intervention deliverers and the target group.

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