Table 2 Structure of the two PPI groups involved in the ABC programme

ABC PPI Group, a programme-wide group that provided input across all aspect of the programme: (N=5)

• An initial group of three members established, which was expanded to five members to strengthen inclusion and diversity (Supplementary Material 1)

• Members had a range of perspectives and lived maternity experiences (including obstetric emergency, neonatal death and high-risk pregnancy), and included under-represented voices

• Members were experienced in maternity research and advocating for improvement, with extensive networks in the maternity stakeholder system

• Two meetings across first half of the programme, and fortnightly meetings across second half of the programme

• All meetings were held online with materials circulated beforehand

• Online whiteboards were used to visually summarise discussion during meetings

• Meetings were facilitated by a senior social scientist (LH), THIS Institute’s Head of Patient and Public Involvement and Engagement (JL) and a public health researcher (BA)

• First two meetings aimed at advising on the interview guides and vignette for a consultation with women and birth partners materials on birth experiences, and supporting recruitment of two new members to enhance diversity

• Subsequent fortnightly meetings aimed to support responsive and sustained involvement and iterative contribution to co-design of all resource. Supplementary Materials 2

Obstetric emergency PPI group, providing input twice on a particular topic (N=15)

• 15 women with experience of an obstetric emergency

• Purposively recruited via 14 Maternity Voices Partnership (MVP) groups [68], aiming to maximise diversity and representation of under-represented voices

• Two meetings across the second half of the programme

• Both meetings were held online with materials circulated beforehand

• Meetings were facilitated by a senior social scientist (LH) and THIS Institute’s Head of Patient and Public Involvement and Engagement (JL).

• Meetings aimed to seek specific input on communication around the obstetric emergency of impacted fetal head at caesarean birth and its management, based on lived experiences of what it was like to be involved in an obstetric emergency.