Background Reducing avoidable harm in maternity services is a priority globally. As well as learning from mistakes, it is important to produce rigorous descriptions of ‘what good looks like’.

Objective We aimed to characterise features of safety in maternity units and to generate a plain language framework that could be used to guide learning and improvement.

Methods We conducted a multisite ethnography involving 401 hours of non-participant observations 33 semistructured interviews with staff across six maternity units, and a stakeholder consultation involving 65 semistructured telephone interviews and one focus group.

Results We identified seven features of safety in maternity units and summarised them into a framework, named For Us (For Unit Safety). The features include: (1) commitment to safety and improvement at all levels, with everyone involved; (2) technical competence, supported by formal training and informal learning; (3) teamwork, cooperation and positive working relationships; (4) constant reinforcing of safe, ethical and respectful behaviours; (5) multiple problem-sensing systems, used as basis of action; (6) systems and processes designed for safety, and regularly reviewed and optimised; (7) effective coordination and ability to mobilise quickly. These features appear to have a synergistic character, such that each feature is necessary but not sufficient on its own: the features operate in concert through multiple forms of feedback and amplification.

Conclusions This large qualitative study has enabled the generation of a new plain language framework—For Us—that identifies the behaviours and practices that appear to be features of safe care in hospital-based maternity units.