Crichton 1962.

Study characteristics
Methods	Prospective randomised controlled trial in a hospital setting. 2 treatment arms.
Participants	305 labouring women randomised whose attending doctors requested pelvimetry by radiography.
Interventions	Intervention group: 151 women allocated to intrapartum x‐ray pelvimetry when requested by staff. Comparison group: 154 women allocated to no pelvimetry when requested by staff.
Outcomes	Caesarean section/symphysiotomy Perinatal mortality Asphyxia Maternal survival
Notes	No electronic fetal heart rate monitoring used. No information on the indication for X‐ray pelvimetry except that the doctor wished to have it performed on a woman in labour. No blinding of staff, this could possibly affect results if staff requesting pelvimetry are not able to use it. Hospital setting in country not explicitly named but likely to be South Africa. Funding source: not stated. Dates study was conducted: unclear Declarations of interest of primary researchers: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Intrapartum radiography‐when desired by staff‐would only be permitted if an envelope removed front the box contained permission typed "yes" as opposed to the refusal typed "no". Obviously no exceptions were permitted this rule."
Allocation concealment (selection bias)	Unclear risk	No mention in text.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Called "double‐blind" but no further details are given. Staff would have been aware of whether or not pelvimetry was permitted, women may not have been told. Clinical management may have been affected by knowledge of allocation.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Assessment of some of the outcomes (e.g. neonatal well‐being) may have been affected by lack of blinding. Assessment may have been by staff aware of allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Appears complete.
Selective reporting (reporting bias)	Unclear risk	Protocol not available, outcomes not pre‐specified in methods.
Other bias	Unclear risk	No other bias apparent but baseline characteristics of participants not reported.