The Boost Brittle Bones Before Birth (BOOSTB4) clinical trial is investigating the safety and efficacy of transplanting fetal derived mesenchymal stromal cells (MSCs) prenatally and/or in early postnatal life to treat severe Osteogenesis Imperfecta (OI). This study aimed to explore stakeholder views to understand perceived benefits or concerns, identify ethical issues and establish protocols for support and counselling. Semi-structured qualitative interviews were conducted with three groups; 1. Adults affected with OI, with and without children, and parents of children affected with OI; 2. Health professionals who work with patients with OI; 3. Patient advocates from relevant patient support groups. Interviews were digitally recorded, transcribed verbatim and analysed using thematic analysis. Interviews with 56 participants revealed generally positive views towards using fetal MSC transplantation to treat OI. Early treatment was considered advantageous for preventing fractures and reducing severity and could bring psychological benefits for parents. Common concerns were procedure safety, short/long-term side effects and whether transplantation would be effective. Difficulties inherent in decision-making were frequently discussed, as treatment efficacy is unknown and, by necessity, parents will make decisions at a time when they are vulnerable. Support needs may differ where there is a family history of OI compared to an unexpected diagnosis of OI. Explaining fetal MSC transplantation in a way that all parents can understand, clear expectation setting, psychological support and time for reflection during the decision-making process will be crucial to allow parents to make informed decisions about participation in the BOOSTB4 clinical trial.