One of the numerous challenges preterm birth poses for parents and physicians is prognostic disclosure. Prognoses are based on scientific evidence and medical experience. They are subject to individual assessment and will generally remain uncertain with regard to the individual. This can result in differences in prognostic framing and thus affect the recipients' perception. In neonatology, data on the effects of prognostic framing are scarce. In particular, it is unclear whether parents prefer a more optimistic or a more pessimistic prognostic framing. To explore parents' preferences concerning prognostic framing and its effects on parent-reported outcomes and experiences. To identify predictors (demographic, psychological) of parents' communication preferences. Unblinded, randomized controlled crossover trial (RCT) at the Division of Neonatology of the University Medical Center Mainz, Germany, including German-speaking parents or guardians of infants born preterm between 2010 and 2019 with a birth weight < 1500 g. Inclusion of up to 204 families is planned, with possible revision according to a blinded sample size reassessment. Embedded in an online survey and in pre-specified order, participants will watch two video vignettes depicting a more optimistic vs. a more pessimistic framing in prognostic disclosure to parents of a preterm infant. Apart from prognostic framing, all other aspects of physician-parent communication are standardized in both videos. At baseline and after each video, participants complete a two-part online questionnaire (baseline and post-intervention). Primary outcome is the preference for either a more optimistic or a more pessimistic prognostic framing. Secondary outcomes include changes in state-anxiety (STAI-SKD), satisfaction with prognostic framing, evaluation of prognosis, future optimism and hope, preparedness for shared decision-making (each assessed using customized questions), and general impression (customized question), professionalism (adapted from GMC Patient Questionnaire) and compassion (Physician Compassion Questionnaire) of the consulting physician. This RCT will explore parents' preferences concerning prognostic framing and its effects on physician-parent communication. Results may contribute to a better understanding of parental needs in prognostic disclosure and will be instrumental for a broad audience of clinicians, scientists, and ethicists. German Clinical Trials Register DRKS00024466 . Registered on April 16, 2021.