Methods	Randomised trial.
Participants	120 women recruited in a hospital in the Zhongshan region of China Inclusion criteria: primiparous women with normal fetal position Exclusion criteria: women with congenital heart disease, twin pregnancy or hypertension
Interventions	Intervention: TENS to 4 bilateral acupuncture points. The frequency and intensity of TENS was adjusted according to tolerance. It was not clear how or by whom the TENS were operated Comparison groups: two groups each of 30 women, one group received oxytocin and one group received no intervention (“all drugs and therapeutic methods were suspended”). The latter group were used as the control group for this review
Outcomes	Rating of pain (assessed by clinician and women), pain progression, length of time for full cervical dilatation, blood cortisol content and measures of uterine contraction
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	Described as “randomly divided”.
Blinding (performance bias and detection bias) Participants	High risk	The control group received no intervention.
Blinding (performance bias and detection bias) Clinical staff	High risk	Not feasible.
Blinding (performance bias and detection bias) Outcome assessor	High risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No exclusions or drop-outs from the study apparent.
Other bias	Unclear risk	Unclear.