Evaluation of the Effectiveness of Transcutaneous Electrical Nerve Stimulation During Labor.

This study evaluates the effectiveness of the Transcutaneus Electric Nerve Stimulation (TENS) during the labour. TENS is a low frequency electrotherapy technique, analgesic type, generally used in musculoskeletal pathology. The investigators will have three groups of participants to be administered the TENS, a different dose in two groups, while the third will correspond to placebo. The hypothesis of the study is to verify if the TENS is effective as a non-pharmacological method in the relief of pain during childbirth