Pain relief in labor by transcutaneous electrical nerve stimulation. Testing of a modified stimulation technique and evaluation of the neurological and biochemical condition of the newborn infant.

In this prospective randomized study of pain relief in labor, the effect of transcutaneous electrical nerve stimulation (TNS) performed over both the low-back and suprapubic region was evaluated and compared with a control group not receiving TNS. Both high frequency and pulse train TNS were used. The study included 24 induced labors. In the TNS group, conventional methods were added when needed, while in the control group only conventional methods were used. Assessment of low-back and suprapubic pain was performed by the parturient each hour during the first stage. In the TNS group most of the parturients reported minimal or moderate low-back pain throughout labor, while parturients in the control group reported an increased intensity of low-back pain as labor progressed. The effect of suprapubic pain was insignificant in both groups. Neither TNS nor nitrous oxide-oxygen mixture and pethidine could reduce this pain component. Course of labor, uterine activity and fetal heart patterns were similar in the two groups. The neonates were evaluated with Apgar score, assays of blood samples from the umbilical vein including blood lactate, plasma hypoxanthine and blood gas, and neurobehavioral assessment on two occasions. All newborn infants were in good condition and no significant differences between the two groups could be demonstrated.