Kennell 1991.

Methods	RCT of continuous support versus usual care with an 'inconspicuous observer' plus a retrospective non‐random control group. This review is restricted to comparisons of the outcomes of the participants who were randomly assigned
Participants	412 nulliparous women (212 in support group and 200 in observed group) were part of the RCT. They were aged 13 to 34 years, with singleton, term, healthy pregnancies, many not English‐speaking, in active labour at a public hospital in Texas which provides care for low‐income patients
Interventions	The description of the setting, the participants, and the type of care echo developing world conditions. All women laboured in a large 12‐bed room. For the women in the support group a doula stayed by their bedside and gave continuous support. For those in the observed group they had the routine intermittent presence of a nurse and continuous presence of an "inconspicuous observer" who "kept a record of staff contact, interaction and procedures". The observer was away from the beside and never spoke to the labouring woman
Outcomes	Analgesia/anaesthesia, labour length, artificial oxytocin use, method of birth, complications (mother and baby), neonatal health, number of women who rated their experience as negative
Notes	In instances in which outcome data (such as analgesia/anaesthesia use) in the published report were only provided for subgroups, the primary author was contacted and he provided complete outcome data for all women who were originally randomised. Family members were not allowed to be present. Epidural analgesia was available and EFM was used routinely Dates of study: not clear, accepted by journal 1991 Funding: grant HD 16915 awarded by the National Institute of Child Health and Human Development, Bethesda, Md; by the Arthur Vining Davis Foundations, Jacksonville, and by the Pittway Corporation Charitable Foundations, Chicago. Conflicts of interest: not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as random, however participants were randomised to the control group if they were eligible, but admitted to the hospital on days that doulas were already assigned to other patients
Allocation concealment (selection bias)	Low risk	"Randomly assigned" is stated in the report. In the protocol for the trial it states "numbered opaque envelopes" would be used. The envelopes "would contain the random assignments of the women to control or treatment groups and would be numbered sequentially"
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and labour ward staff not blinded to group assignment
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear who assessed the outcome data
Incomplete outcome data (attrition bias) All outcomes	Low risk	There is some discrepancy in the number of women enrolled in the study. The report states 412 were enrolled and reports outcome data on all 412 women. But it also states that "14 women that agreed to participate were not included in the study." The reasons for not including them seem to be events that would happen after randomisation ‐ e.g. transferred due to staffing limitations, withdrew, undetected breech, interrupted observations, etc., and thus the sample appears to have numbered 426. Data are reported for 412 women (96.7% of 426)
Selective reporting (reporting bias)	Low risk	All outcomes were reported
Other bias	Low risk	No other sources of bias noted