Table 2 Feasibility measures: assessment criteria, timing of measurement and data collection method

Number available in each catchment

Number of potentially eligible individuals booking for maternity care in the three maternity services

At booking into maternity services

Collected by NHS administrative staff and researchers

Consent to randomisation (recruitment rate)

The proportion of those invited to participate, who consented

At recruitment

Collected by researchers recruiting at the three units

Uptake of intervention

Number assigned to intervention who attended at least one group session

Throughout intervention period

Derived from records kept by the midwives facilitating Pregnancy Circles

Retention in intervention

Total numbers who attended at least 6 of the 8 Pregnancy Circles sessions (or for those who gave birth early, attendance at 75% of the sessions prior to the birth)

End of the intervention period

Reasons for non-take up or non-attendance at certain sessions were gathered via a range of routes including by midwives over the phone when following up non-attendance, in interviews and via hospital records

Questionnaire completion rates

Overall response rate and completion rate for each measure within the questionnaire

Each of the two follow-up questionnaire points

Overall response rate calculated based on non-response after three attempts utilising a range of routes (e.g. email, postal, telephone)