Objective: To explore implementation of two intrapartum trials with compelling findings: BUMPES (position in second stage of labour in nulliparous women with epidural), and RESPITE (remifentanil intravenous patient-controlled analgesia). Design: Qualitative interview study. Setting: UK NHS Trusts and Universities. Sample: Purposively sampled investigators from RESPITE and BUMPES trials and clinicians providing intrapartum care: midwives, anaesthetists and obstetricians recruited using existing networks and snowball sampling. Methods: Semi-structured virtual interviews. Thematic analysis was underpinned by Capability Opportunity Motivation Behaviour Change Framework. Results: Twenty-nine interview participants across 19 maternity units: 11 clinical academics, 10 midwives, 4 obstetricians, 4 anaesthetists. Most (25/29) were aware of one or both trials. BUMPES had been implemented in 4/19 units (one original trial site) and RESPITE in 3/19 units (two trial sites). Access to sufficient resources, training, exposure to interventions, support from leaders, and post-trial dissemination and implementation activities all facilitated uptake of interventions. Some clinicians were opposed to the intervention or disagreed with trial conclusions. However competing priorities in terms of staff time and a plethora of initiatives in maternity care, emerged as key barrier to implementation. Conclusions: Compelling trial findings were not implemented widely, and numerous barriers and facilitators were identified. Large-scale improvement programmes and evidence-based national guidelines may mean single trials have limited potential to change practice. There is a need to examine how intervention implementation is prioritised to optimise safety outcomes in the context of workforce restrictions, limited resources and large arrays of competing priorities including statutory requirements, that have increased in maternity care.