Methods	RCT.
Participants	Study in Quebec, Canada at a rural hospital. Women at low risk admitted for delivery 35 women included in the analyses. Inclusion criteria: term pregnancy (more than 36 weeks’ gestation), women in active first stage labour who complained of low back pain with no obstetric or medical complications
Interventions	Intervention group: TENS to lower back operated by women. Comparison group 1: intracutaneous sterile water to lumbar sacral region (4 injections) Comparison group 2: routine care with massage, whirlpool baths and ambulation encouraged
Outcomes	Low back pain, use of other analgesia, satisfaction with labour and delivery measured in postnatal period. Pain measured on a 10 cm VAS in millimetres
Notes	The SDs reported for the pain scores were very much lower than might be expected with a VAS and appeared incorrect for some results; where SDs appeared incorrect we have not included data in data and analyses tables
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Table of random numbers in balanced blocks.
Allocation concealment (selection bias)	Low risk	Sealed, sequentially numbered, opaque envelopes.
Blinding (performance bias and detection bias) Participants	High risk	Different interventions.
Blinding (performance bias and detection bias) Clinical staff	High risk	Different interventions.
Blinding (performance bias and detection bias) Outcome assessor	High risk	Different interventions.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Small loss to follow up but very low recruitment to this study
Other bias	Unclear risk	Of 304 women informed of the study, only 35 were recruited.