Lim 2010.

Study characteristics
Methods	Randomised double‐blinded controlled clinical trial
Participants	Setting: recruited from KK Women's and Children's Hospital, Singapore Sample size: N = 51 (N completers = 50) Participants: age not provided Inclusion criteria: healthy nulliparous parturients with cephalic presentation at > 36 weeks gestation in early, spontaneous labour (cervical dilation < 5 cm) 1 woman from CEI group excluded as epidural catheter was blocked and re‐sited 2 hours after initiation of CSE
Interventions	AMB (n = 25): 2.5 mL epidural boluses of 0.1% ropivacaine with fentanyl 2 µg/mL, infused over a 2‐minute period, every 15 min. The first bolus was given 7.5 min after the intrathecal injection BI (n = 25): 0.1% ropivacaine with fentanyl 2 µg/mL at 10 mL/hour, delivered by syringe pump and initiated immediately after the intrathecal injection
Outcomes	Rate of breakthrough pain with need for anaesthetic intervention Rate of caesarean delivery Rate of instrumental delivery Duration of labour Time‐weighted consumption of LA Maternal satisfaction Apgar scores
Notes	Study dates: 18 February to 19 March 2007 Funding sources not declared No conflict of interests declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method of randomisation was not stated: Quote:"This was a randomised, double‐blind controlled clinical trial. We allocated the participants to the AIB and CEI groups using a sealed opaque envelope, which was opened after recruitment by the anaesthetist who was to perform the epidural."
Allocation concealment (selection bias)	Low risk	Allocation concealment via sealed opaque envelopes: Quote:"We allocated the participants to the AIB and CEI groups using a sealed opaque envelope..."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and clinical team were blinded: Quote:"The parturient was blinded to the group allocation. All baseline data were gathered by the attending nurse/midwife, who was also blinded to participant study group allocation."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors were blinded: Quote:"The parturient was blinded to the group allocation. All baseline data were gathered by the attending nurse/midwife, who was also blinded to participant study group allocation."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition; 1 participant out of 51 did not complete 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 calculation: sample size was computed to detect a 30% difference in the incidence of breakthrough pain