Objective To describe maternity nurses' perspectives on how they contribute to safety during labour and birth at two urban academic medical centres in the United States.

Design Grounded theory: data were collected using semistructured, open-ended interviews and participant observations with registered nurses (RNs) in two inpatient maternity settings. Data were analysed simultaneously using constant comparison, and dimensional and situational analysis.

Participants Purposive sample of 12 RNs working in the two maternity units.

Findings Safety was broadly conceptualised by RNs as protecting the physical, psychological and emotional wellbeing of a woman and her family. During labour and birth, safety was maintained by RNs through “skilful anticipation” of situational potential. This required integration of medical and technical knowledge and skill with intimate knowledge of the woman and the operational context of care to achieve accurate situation awareness and appropriate future planning. Conditions and processes promoting skilful anticipation included being prepared, knowing, and envisioning the whole picture.

Conclusions In the two settings, maternity RNs made active contributions to safe birth in the context of constrained resources through preparing the environment, anticipating potential problems and trapping errors before they reached the patient. The contributions of maternity nurses to team situation awareness and to creating safety need to be appreciated and administratively supported. Continued research with RNs may reveal previously unrecognised opportunities for safety improvements.