Objectives To explore barriers and facilitators to midwifery practice of intermittent auscultation according to national guidance in the UK. Design Multisite ethnographic study using observations of practice, semistructured interviews and informal conversations. Framework analysis using the Consolidated Framework for Implementation Research (CFIR). Setting 11 maternity units across seven NHS maternity services in England and Wales in 2024. Participants Midwives and other maternity care professionals involved in fetal monitoring during labour. Intervention ‘Intermittent auscultation’ (IA), or listening to the fetal heart rate at regular intervals, to monitor fetal well-being during active labour. Outcome measures Not applicable. Results IA monitoring was frequently observed to be marginalised due to national and local pressures. IA is a complex skill that requires expertise and practice to develop and maintain. However, lack of a robust evidence base for IA methods is a further barrier to implementation. The study uncovered examples of facilitators that include: leadership engagement, access to knowledge and information supported in mentorship programmes and peer support models. These features created micro-environments where IA was valued, supported and integrated into care. Conclusions Our study highlights the significant impact of multilevel factors on the implementation of IA within UK maternity care. However, when organisational readiness, strong leadership engagement and supportive conditions are present, IA can be delivered in accordance with guidance. These findings underscore the need to align policy, infrastructure and organisational culture to sustain evidence-based, woman-centred practices such as IA.