Parsons 1985.

Study characteristics
Methods	Prospective randomised study at the University of Illinois Hospital, Chicago. Women individually randomised by hospital number. 2 treatment arms.
Participants	200 women randomised when admitted to hospital for induction or augmentation of labour using oxytocin. Inclusion criteria: primigravida with vertex presentation.
Interventions	Intervention group: 102 women allocated to receive clinical and X‐ray pelvimetry before induction or augmentation. Comparison group: 98 women allocated to receive no X‐ray pelvimetry before induction or augmentation. This group all received clinical pelvimetry.
Outcomes	Length of labour Length of ruptured membranes Length of oxytocin administration Type of delivery Apgar scores Birthweight
Notes	All women monitored with electronic fetal heart rate monitoring and intrauterine pressure monitors. 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)	High risk	"Patients were randomised into two groups by hospital number."
Allocation concealment (selection bias)	High risk	Randomisation by hospital number means that staff recruiting women to the study may have been able to anticipate randomisation group.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of patients is not likely with this intervention. "The management of all patients then proceeded on the basis of clinical and/or x‐ray evaluation, and the investigators did not participate in the evaluation of the pelvises in the management plan." Does not appear staff were blinded which could have affected treatment of both intervention and comparison groups.
Blinding of outcome assessment (detection bias) All outcomes	High risk	The recording of outcomes was by a member of staff caring for the patient who would be aware of randomisation group. It was stated that the investigators did not participate in the evaluation of pelvises but all other clinical staff would be aware of the intervention.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Appears complete, reports outcomes for all participants.
Selective reporting (reporting bias)	Unclear risk	No protocol but outcomes stated in methods section. Length of labour data reported narratively, no actual data.
Other bias	Low risk	No baseline imbalance reported. No other bias apparent.