Statistical analysis
BREECH PRESENTATION, RECRUITMENT
The sample size of 104 women was calculated to enable estimation of a recruitment rate between 20–80%, with a 95% confidence interval, within ±10%. For a site with an average of 25 women it would be possible to estimate the same recruitment rate within ±18%.Primary outcomes were assessed by intention to treat according to randomisation arm. Participants who withdrew their data were excluded from analysis. For recruitment rates, mean and confidence intervals were calculated using a one-sample t-test. Site opening times were very unpredictable during the COVID-19 pandemic, and one site closed early. Therefore, recruitment figures were calculated according to the number of months each site was open. Secondary outcomes, safety and feasibility outcomes were assessed by intention to treat (randomisation arm and cohort).The OptiBreech care intervention was designed to enable women to choose the option of VBB, which women reported as being unavailable or inaccessible under standard care. Acceptance was measured as the rate of planning a VBB. This was measured following initial counselling and ‘at any point,’ including after failed/non-attempted ECV. The significance of the difference in percentage of participants planning a VBB was calculated using a Fisher exact test. The 95% confidence intervals were calculated using a two-sided z-test (Wald and with Agresti-Caffo adjustments). Although the feasibility pilot was not designed and not powered to detect significant differences in outcomes, the significance of this finding is reported because it was the basis of the Trial Steering Committee (TSC) decision to stop randomisation early, during an unplanned interim analysis.Planned sub-group analysis was performed for the following groups, from the entire cohort: 1) those who planned a VBB at any point versus those who had not; 2) actual VBBs versus vaginal cephalic births; and 3) presentation on admission for labour/birth care. These subgroup analyses were chosen because 1) this is the comparison most often used in large observational cohort studies; 2) this comparison was prioritised by PPI group members; and 3) cephalic presentation at birth is evaluated as an outcome in Cochrane Reviews concerning the management of breech presentation at term. An unplanned sub-group analysis was performed for minoritised ethnicity (non-British and Black or Brown/mixed cohorts), as advocated by the PPI group.Data were analysed using SPSS Version 28. For the feasibility study, because of the small sample size and non-clinical primary outcomes, the ethics review approved the Trial Steering Committee to serve as the Data Monitoring Committee.