Abstract Objective: To develop a core outcome set for trials investigating interventions to prevent stillbirth. Design Outcomes identified from a systematic literature review and semi-structured interviews with parents were entered into a two-round online Delphi survey. Setting and population Australia and UK Methods: Delphi survey and focus group/consensus meetings Results: A core outcome set containing 11 outcomes in two categories. Five outcomes were related to the mother; fetal loss (to include both miscarriage and stillbirth), onset of and mode of delivery (to include induced/spontaneous and instrumental/vaginal/CS), maternal mortality or near miss (according to WHO definition), psychological and social impact on the mother (assessed using a validated tool appropriate to context), women’s knowledge. Six outcomes were related to the baby; timing of stillbirth (antepartum/intrapartum), neonatal mortality, gestational age at delivery, birthweight (g), congenital anomaly, NICU/SCBU or other higher-level neonatal care length of stay (days). Conclusion Implementation and dissemination of this core outcome set in future trials will contribute towards coordinated outcome reporting and advancing usefulness of research to guide clinical practice. Keywords: Core outcomes, core outcome set, Stillbirth, Delphi