Objective: Refine the programme theory for OptiBreech Care Design: Concurrent mixed methods implementation process evaluation Setting: 6 NHS hospitals in England participating in the OptiBreech 1 Feasibility Study Sample: 15 women planning a vaginal breech birth at term and 6 breech lead midwives Methods: Outcomes were recorded on case report forms and descriptively analysed. Interviews were recorded, transcribed and analysed using the Theoretical Framework of Acceptability. Iterative analysis informed subsequent interviews and the on-going process of implementation across sites. Main Outcome Measures: Acceptability of service delivery models and their outcomes. Results: Actively recruiting Trusts implemented services through a dedicated clinic and/or a proficient intrapartum support service, organised and provided primarily by a Breech Specialist Midwife. While we identified challenges, this model has achieved 93% fidelity to the intervention’s goal of ensuring attendance of OptiBreech-trained professionals at vaginal breech births, and it is highly acceptable to women. Our initial suggested model of a multi-disciplinary team composed of 5 obstetricians and 5 midwives does not appear feasible, due to very low overall current breech experience levels and the context of current pressures on NHS services. Conclusions: Appointment of a Breech Specialist Midwife, whose role is to co-ordinate a dedicated clinic, training and a proficient intrapartum care team, appears to be highly acceptable to women. This model appears to be a feasible implementation strategy, in order to test the safety and effectiveness of OptiBreech Care in a clinical trial, but further work needs to be done to develop sustainability.

Objective: To test the predictive value of the Physiological Breech Birth Algorithm. Design: Retrospective case-control study Setting: Teaching Hospital, United Kingdom Population/sample: Cases were all vaginal breech births >37 weeks’ gestation where neonatal admission or death occurred between April 2012 and April 2020. Controls were the two term breech births without admission immediately prior to the cases. Methods: Data was collected from intrapartum care records and analysed using SPSS v26 statistical software. The chi-square test was used to determine association between exposure to the variables of interest and admission to the neonatal unit. Multiple logistic regression was used to test the predictive value of delays defined as non-adherence to the Algorithm. Main outcome measures: Intervals between the start of labour, the start of second stage of labour and various stages of emergence (presenting part, buttocks, pelvis, arms, head). Results: Logistic regressing modelling using the Algorithm time frames had an 84.2% accuracy, a sensitivity of 66.7% and a specificity of 92.3%. Delays between umbilicus and head >3 minutes (OR: 9.508 [95% CI: 1.390-65.046] p=0.022) and from buttocks on the perineum to head >7 minutes (OR: 6.682 [95% CI: 0.940-41.990] p=0.058) showed the most effect. Lengths of time until the first intervention were also longer among the cases, suggesting that at least some of this delay is modifiable. Conclusions: Improved recognition of delay and efficient assistance may help improve vaginal breech birth outcomes. Further research should determine whether training based on the Physiological Breech Birth Algorithm can reduce neonatal admissions.