Nielsen 2007.

Methods	Cluster‐randomised trial
Participants	Who: All obstetricians, anaesthesiologists, and nurses Number: 1307 Proportion of eligible staff participating: Not reported
Interventions	Intervention description: Teamwork training curriculum for labour and delivery. After their training, instructors returned to their hospitals to train local staff. They also developed a contingency team within the hospital consisting of experienced practitioners to respond in a co‐ordinated way to obstetric emergencies. Control: No training Location: Instructors were trained away from their hospitals, they trained staff at their hospitals. Delivered by: Clinical staff at intervention hospitals attended instructor training. Length: The instructor training was 3 days; there is no description of the local intervention. Duration: 4‐month training period
Outcomes	Outcomes: Adverse outcome index, registration to provider assessment Follow‐up: 2 months baseline, 4‐month training period, 5‐month post‐implementation period
Population studied	Description: Pregnant women over 20 weeks gestation admitted to study sites Number: 28,536 women; control: 14,336, intervention: 14,200
Funding Source	Department of Defense and American Research Institute
Study Setting	Labour and delivery units and 15 civilian/military hospitals in USA
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Clear description of how randomisation took place, using random numbers tables and random assignment of alphanumeric labels to each hospital
Allocation concealment (selection bias)	Low risk	Masking to hospital but not whether military or civilian
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not clear
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Mentioned but how missing data were dealt with is not discussed
Selective reporting (reporting bias)	Low risk	All outcomes reported.
Other bias	High risk	Contingency team created as part of team‐training intervention.