ObjectivesAs part of the FERN feasibility study, this qualitative research aimed to explore parents’ and clinicians’ views on the acceptability, feasibility and design of a randomised controlled trial (RCT) of active intervention versus expectant management in monochorionic (MC) diamniotic twin pregnancies with early-onset (prior to 24 weeks) selective fetal growth restriction (sFGR). Interventions could include laser treatment or selective termination which could lead to the death or serious disability of one or both twins.DesignQualitative semi-structured interviews with parents and clinicians. Data were analysed using reflexive thematic analysis and considered against the Principles of Biomedical Ethics.Participants and settingWe interviewed 19 UK parents experiencing (six mothers, two partners) or had recently experienced (eight mothers, three partners) early-onset sFGR in MC twin pregnancy and 14 specialist clinicians from the UK and Europe.ResultsParticipants viewed the proposed RCT as ‘ethically murky’ because they believed that the management of sFGR in MC twin pregnancy should be individualised according to the type and severity of sFGR. Clinicians prioritised the gestational age, size, decrease in growth velocity, access to the placental vessels and acceptability of intervention for parents. Discussions and decision-making about selective termination appeared to cause long-term harm (maleficence). The most important outcome for parents and clinicians was ‘live birth’. For clinicians, this was the live birth of at least one twin. For parents, this meant the live birth of both twins, even if this meant that their babies had neurodevelopmental impairment or disabilities.ConclusionsAll three pregnancy management approaches for sFGR in MC twin pregnancy carry risks and benefits, and the ultimate goal for parents is to receive individualised care to achieve the best possible outcome for both twins. An RCT was not acceptable to parents or clinicians or seen as ethically appropriate. Alternative study designs should be considered to answer this important research question.