Table 1 A summary of the content presented at each meeting and pre- and post-meeting activities completed by researchers

Meeting 1 (investigative team)

Seven of the eight team members attended the meeting

Explaining how the study will proceed, presenting the findings from the preliminary research displayed in Fig. 1, and refining the structure of the co-design online discussions

Summarizing study methods and developing pre-reading materials for end users to view before their first meeting. Materials included a summary of preliminary research

Stage 1, Steps 1–4 (defining the problem, identifying the target behaviour, specifying the target behaviour and identifying what needs to change)

Meeting 2 (end users)

Held on two separate days, with 6 attendees on the first day and 12 attendees on the second

Using the APEASE criteria to brainstorm intervention ideas to address barriers to the provision of CVD prevention for women after HDP in primary care

Translated end users’ suggestions into 10 intervention functions and policy categories

Stage 2, Step 5 (identifying intervention functions) and Step 6 (identifying policy categories)

Meeting 3 (investigative team)

Four of the members (one obstetrician, midwife, GP and representative of women with HDP) completed the pre-meeting APEASE activity

Seven of the eight team members attended the meeting

Using three of the APEASE criteria, the investigative team rated each of the 10 proposed intervention ideas, and then discussed and voted on their preferred intervention functions and policy categories

Calculated scores from the APEASE criteria and voting activity

Commenced BCT coding of the proposed intervention

Developed a translated summary of the intervention functions, policy categories and BCTs for end users

Finalized Stage 2, Step 5 (identifying intervention functions) and Step 6 (identifying policy categories)

Meeting 4 (end users)

Of the 18 end users, 17 completed a SWOT analysis of the proposed intervention ideas prior to the meeting

A total of 12 end users attended the meeting (one obstetrician, two GPs, three midwives and 6 women with a history of HDP)

Appraisal of the proposed intervention via SWOT analysis (individual activity via online questionnaire facilitated on REDCap) and group discussion and voting on the delivery mode

Thematic analysis of the SWOT analyses

Summarized version of the intervention, presented as each component of the BCW

Stage 3, Step 7 (BCTs) and Step 8 (mode of delivery)

Meeting 5 (investigative team)

Email consultation

Final feedback on the intervention plan via email, answering 2–3 questions: (1) does intervention parts 1 and 2 address the relevant barriers; (2) do you approve this intervention plan as a final version; and (3) if not, do you have any issues with the intervention plan, and if so, what would you change?

Summary of intervention plan, summary of study findings and manuscript preparation