Table 2 Examples of interview questions

Intervention group

 • What did you like most about attending the Mamas in Harmony sessions? Why? (Prompts: specifically ask about singing component and social support component, for example in terms of mood, confidence, social support, attachment/bonding with baby)

 • Was there anything you did not like about the Mamas in Harmony sessions? Why? Is there anything that could have been done to help with that?

 • Do you feel sessions suited you and your baby? If yes, in what way? (Prompts: what part/s of the session felt relevant/supportive/helpful/calming/nurturing/other description used by mother)

 • Do you feel you and your baby have benefited from the Mamas in Harmony sessions? In what way? (Prompts: how you feel about yourself/your baby/your needs, how you feel about singing, the relationship you have with your baby, learned new skills or ideas, being part of a group, opportunity to connect with other mothers)

 • Do you feel duration of each session was about right? (Prompt: for music component, for social support component)

 • Do you feel the number of sessions offered was enough to be beneficial for you and your baby?

 • Do you feel the venue where sessions were held was right? (Prompt: comfortable, enough space, felt able to relax)

Control group

 • Did you feel you were given sufficient information about the study before you decided to take part?

 • Did you complete your questionnaires online (Qualtrics platform) or a paper copy?

If Qualtrics

  o Did you encounter any difficulties? (Prompts: navigating between questions, saving and returning to it at a later date, submitting)

  o Did you find the questionnaire layout clear and easy to follow?

  o Did you complete all the questions within each questionnaire?

  o If not, what was the reason for that? (Prompts: too time -consuming, difficult to understand, information requested was too sensitive)

Intervention facilitator/s

 • What did you enjoy most about delivering the Mamas in Harmony sessions?

 • Is there anything you did not enjoy about delivering Mamas in Harmony sessions?

 • What do you think worked well?

 • What do you think did not work well?

 • Do you feel sessions were tailored and appropriate for mothers and babies?

 • Were there any challenges you encountered in delivering Mamas in Harmony sessions? (Prompt: with mums, with babies, with support staff, with the venue, with the intervention materials)