To investigate whether simulation-based obstetric team training in a simulation centre improves patient outcome. Women with a singleton pregnancy beyond 24 weeks of gestation. Random allocation of obstetric units to a 1-day, multi-professional, simulation-based team training focusing on crew resource management (CRM) in a simulation centre or to no such team training. Intention-to-treat analyses were performed at the cluster level, including a measurement 1 year prior to the intervention.