ImportanceManagement of maternal cardiac arrest (MCA) requires understanding the unique physiology of pregnancy and modifications to life support. Health care professionals have historically demonstrated inadequate knowledge and skills necessary to treat MCA.ObjectiveTo evaluate the effect of Obstetric Life Support (OBLS) education on health care professionals’ cognitive performance, skills, and self-efficacy in managing MCA.Design, Setting, and ParticipantsIn this single-masked randomized clinical trial, 46 health care professionals, including emergency medical service and hospital staff representing diverse specialties, were randomized to intervention or control groups at a single academic medical center in Farmington, Connecticut between May 1, 2022, and July 23, 2023.InterventionThe intervention group received OBLS education, which included a blended learning curriculum with simulation-based training on common maternal medical emergencies that lead to MCA. Participants were assessed for knowledge, confidence, and skills (eg, megacode scores as team leaders during MCA simulations). Intervention participants were compared with control group participants who received no OBLS education.Main Outcomes and MeasuresThe primary outcome was cognitive scores. Secondary outcomes included megacode scores rated by experienced OBLS instructors masked to assignment groups, combined assessment pass rates, and cognitive and confidence scores at baseline and 6 and 12 months after education. Data were analyzed from January 2024 to May 2024.ResultsForty-six participants (mean [SD] age, 41.1 [16.2] years; 24 [52%] women) were randomized. Despite most participants holding certification in basic and advanced cardiac life support, significant between-group differences were identified in knowledge, skills, and confidence. Mean (SD) cognitive scores were 79.5% (9.4%) in the intervention group vs 63.4% (12.3%) in the control group (P < .001). Mean (SD) megacode skills were higher in the intervention vs control group (91.0% [5.0%] vs 61.0% [12.0%], P < .001), as were confidence scores (72.7 [13.3] vs 56.2 [17.9] points, P = .002). Combined assessment pass rates were 90% in the intervention group compared with 10% in the control group (P < .001).Conclusions and RelevanceIn this randomized clinical trial, OBLS education significantly improved health care professionals’ knowledge, skills, and confidence in managing MCA. These findings underscore the urgent need for implementation of a standardized MCA curriculum nationwide, especially as the US continues to face unacceptably high maternal mortality rates.Trial RegistrationClinicalTrials.gov Identifier: NCT05355519