Transcutaneous electrical nerve stimulation with the injection of pethidine and promethazine in the labor pain reduction: A randomized controlled trial.

Background: The use of transcutaneous electrical nerve stimulation (TENS) to relieve labor pain remains controversial and existing evidence is neither strong nor consistent. This research was designed to compare TENS' effect with the injection of pethidine and promethazine in labor pain reduction. Methods: In this trial, for 45 pregnant women in the active phase of labor, TENS electrodes were placed (two on both arms, and two over the participants' low back) continuously for 120 minutes; and for another group 45 pregnant women, 100 milligrams of pethidine and 250 micrograms of promethazine were injected intramuscularly which could be repeated once at least one hour later. Labor pain and duration, need for labor induction/augmentation/other pain control methods/ instrumental delivery, delivery type, and maternal and newborn complications were measured in both groups. Results: The baseline mean visual analog scale (VAS) score, in the TENS group was 8.51±0.62 and in the pethidine and promethazine groups was 8.37±0.61 (P=0.31). While in a 120min post-intervention, it was 6.29±1.50 and 5.73±1.46 in the TENS group and the pethidine and promethazine group, respectively with no statistically significant difference (P=0.07). The labor duration in the TENS group was 6.61±1.71 hours and in the pethidine and promethazine group was 6.17±2.07 hours, with no statistically significant difference (P=0.33). In addition, no complication was recorded neither in the mothers nor newborns. Conclusion: This study showed that applying TENS in the active labor phase can reduce at least two scores in patient labor pain with no significant complications.