Introduction: Obstetric complications and adverse patient events are often preventable. Teamwork and situational awareness (SA) can improve detection and coordination of critical obstetric (OB) emergencies, subsequently improving decision making and patient outcomes. The purpose of this study was to assess the effectiveness of a team training intervention in improving learning and transfer of teamwork, SA, decision making, and cognitive bias as well as patient outcomes in OB. Method: An adapted TeamSTEPPS training program was delivered to OB clinicians. Training targeted communication, mutual support, situation monitoring, leadership, SA, and cognitive bias. We conducted a repeated measures multilevel evaluation of the training using Kirkpatrick's (1994) framework of training evaluation to determine impact on trainee reactions, learning, transfer, and results. Data were collected using surveys, situational judgment tests (SJTs), observations, and patient chart reviews. Results: Participants perceived the training as useful. Additionally, participants acquired knowledge of communication strategies, though knowledge of other team competencies did not significantly improve nor did self-reported teamwork on the unit. Although SJT decision accuracy did not significantly improve for all scenarios, results of behavioral observation suggest that decision accuracy significantly improved on the job, and there was a marginally significant reduction in babies' hospital length of stay. Discussion: These findings indicate that the training intervention was partially effective, but more work needs to be done to determine the conditions under which training is most effective, and the ways in which to sustain improvements. Future research is needed to confirm its generalizability to additional OB units and departments.