O'Cathain 2002.

Methods	Study design: cluster‐randomized trial Unit of allocation: group of providers Unit of analysis: patient Power calculation: done
Participants	Care setting: primary care and ambulatory care (maternity units); UK Health professionals: unknown number; physicians in maternity care and midwives; unclear level of training Patients: 10,070; maternity care; female
Interventions	Multifaceted‐intervention: education meeting with staff + distribution of educational materials ; 2 hours (educational meeting) The educational materials consisted of pairs of "Informed Choice" leaflets (given at different periods during gestation) which provided information concerning the benefits and risks of available options concerning labour, and a detailed professional leaflet. The staff in the units receiving the units were trained Usual care (control)
Outcomes	Perceived level of control in decision‐making process (categorical); joint process between healthcare professionals and patients to make decisions.
Notes	Additional information Number of approached patients (eligible): 10,070 Number of patients per physician: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Members of pairs were randomly assigned by tossing a coin to receive the set of leaflets (five intervention units) or to the continue with usual care (five control units)" Page 1
Allocation concealment (selection bias)	Low risk	Quote: "We randomised maternity units rather the individual women because of the risk of women sharing the leaflets in an individual level trial" Page 1
Blinding (performance bias and detection bias) Participant‐reported outcome	Unclear risk	Comment: not specified in the paper.
Incomplete outcome data (attrition bias) Participant‐reported outcome	Unclear risk	Comment: the patients before the intervention are not the same as the patients after intervention. However responses rates were similar across group in each samples. Reasons for non responses were not reported.
Selective reporting (reporting bias)	Unclear risk	Comment: no evidence that outcomes were selectively reported, but no protocol.
Other bias	Low risk	Comment: no evidence of other risk of biases.
Baseline measurement? Participant‐reported outcome	Low risk	Comment: baseline measurements for our primary outcome were reported.
Protection against contamination?	Low risk	Quote: "We randomised maternity units rather the individual women because of the risk of women sharing the leaflets in an individual level trial." page 1
Baseline characteristics patients	Low risk	Comment: see table 1 before the intervention.
Baseline characteristics healthcare professionals	Unclear risk	Comment: no information about professionals.