Fettes 2006.

Study characteristics
Methods	Parallel, randomised controlled trial
Participants	Setting: recruited from Ninewells Hospital and Medical School, Dundee, UK Sample size: N = 47 (N completers = 40) Participants: age 25.8 ± 6.3 years (AMB) and 27.1 ± 4.5 years (BI) Inclusion criteria: ASA I–II primigravid participants with uncomplicated, full‐term (> 37 weeks) pregnancy 7 women were excluded after epidural catheter placement: 3 because of inadequate analgesia at 45 min; and 1 each because of patchy block, epidural filter disconnection, catheter occlusion and study protocol violation
Interventions	AMB (n = 20): ropivacaine 2 mg/mL with fentanyl 2 mg/mL. Hourly boluses, delivered at 2 mL/min, were started 30 min after time zero BI (n = 20): ropivacaine 2 mg/mL with fentanyl 2 mg/mL. Infusion was started immediately at a constant rate of 10 mL/h
Outcomes	Rate of breakthrough pain with need for anaesthetic intervention Rate of caesarean delivery Rate of instrumental delivery Duration of labour Total LA dose Apgar scores
Notes	Study dates not stated Funding sources not declared No conflict of interests declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation by computer‐generated numbers: Quote:"Patients were then randomized (computer generated numbers inserted into opaque envelopes) to receive either a continuous infusion (control group) or intermittent administration (study group)"
Allocation concealment (selection bias)	Unclear risk	Allocation concealment by opaque envelopes, but it was not stated if envelopes were sealed: Quote:"Patients were then randomized (computer generated numbers inserted into opaque envelopes) to receive either a continuous infusion (control group) or intermittent administration (study group)"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding of participants was not stated.  Clinical staff were blinded: Quote:"participants were nursed in the sitting position by staff that were unaware of the treatment used."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of participants was not stated.  The outcome assessor was blinded: Quote:"Observations were made by an assessor 'blind' (the pump was covered) to the mode of drug administration"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition; all randomised patients completed the study.
Selective reporting (reporting bias)	Low risk	All a priori outcomes reported based on published protocol
Other bias	Low risk	Appears to be free of other sources of bias. Sample size of 40 participants (20 per group) would give the study a power of > 0.9 to detect a statistically significant difference in visual analogue pain scores