A Cochrane review included 17 studies with a total of 1 466 women. 13 trials examined transcutaneous electrical nerve stimulation (TENS) applied to the back, 2 to acupuncture points and 2 to the cranium. Overall, there was little difference in pain ratings between TENS and control groups (for severe pain with TENS RR 0.77, 95% CI 0.60 to 1.00; 2 trials, n=147), although women receiving TENS to acupuncture points were less likely to report severe pain (RR 0.41, 95% CI 0.32 to 0.55; 2 trials, n= 190). The majority of women were willing to use it again in a future labour. There was no difference in epidural required concerning TENS to back (RR 0.99, 95% CI 0.59 to 1.67; 5 trials, n=571), TENS to acu-points (RR 0.40, 95% CI 0.08 to 1.97; 1 trial, n=100), or limoge current to cranium (RR 0.11, 95% CI 0.02 to 0.72; 1 trial, n=20). There was no consistent evidence that TENS had any impact on interventions and outcomes in labour. There was little information on outcomes for mothers and babies. No adverse events were reported.
Comment: The quality of evidence is downgraded by several shortcomings in study quality, by inconsistency (heterogeneity in interventions and outcomes), and by imprecise results (limited study size for each comparison).