Objective: To examine i) how ethical frameworks can be used in concrete cases of parent–doctors’ disagreements for extremely preterm infants born in the grey zone to guide such difficult decision-making; and ii) what challenges stakeholders may encounter in using these frameworks. Design: We did a case analysis of a concrete case of parent–doctor disagreement in the grey zone using two ethical frameworks: the best interest standard and the zone of parental discretion. Results: Both ethical frameworks entailed similar advantages and challenges. (...) They have the potential 1) to facilitate decision-making because they follow a structured method; 2) to clarify the situation because all relevant ethical issues are explored; and 3) to facilitate reaching an agreement because all parties can explain their views. We identified three main challenges. First, how to objectively evaluate the risk of severe disability. Second, parents’ interests should be considered but it is not clear to what extent. Third, this is a value-laden situation and different people have different values, meaning that the frameworks are at least partially subjective. Conclusions: These challenges do not mean that the ethical frameworks are faulty; rather, they reflect the complexity and the sensitivity of cases in the grey zone. (shrink)