Pain relief in labor by transcutaneous electrical nerve stimulation. A prospective matched study.

The study evaluated transcutaneous electrical nerve stimulation (TNS) for pain relief in labor, used in parallel with conventional methods. The investigation comprised 566 vaginally delivered women, 283 of whom were given TNS. Pain relief was evaluated with a questionnaire which the women answered shortly after delivery. With a statistical multivariate technique, it was concluded that TNS has a specific effect on pain localized to the back. Few women in either the TNS or the control group reported good relief of pain localized to the suprapubic region. Nitrous oxide-oxygen mixture was used less often in the TNS group than in the controls. Duration of labor and maternal blood loss were comparable in the two groups. The babies borne by primiparae in the TNS group tended to have better Apgar scores. Fewer babies of primiparae in the TNS group required observation for two days or more on the neonatal ward than was the case with the controls. However, the electrical stimulation could not be used optimally as it interfered with monitoring the fetal heart rate in half the cases. It is concluded that although TNS has a good effect on low-back pain and seems to have no negative effects on the mother or child, it is only a complement to conventional methods.