Effects of transcutaneous electrical nerve stimulation applied at different frequencies during labor on hormone levels, labor pain perception, and anxiety: A randomized placebo-controlled single-blind clinical trial

Introduction: There are various non- pharmacological methods for decreasing labor pain which is acute and severe. One method is Transcutaneous Electrical Nerve Stimulation (TENS). This study investigated the effects of TENS applied at different frequencies during labor on hormone levels, labor pain perception and anxiety. The overall aim was to determining the most effective TENS frequency and pulse width.Methods: This randomized-controlled single-blind experimental study included 56 pregnant women who were hospitalized in the delivery unit of a public hospital in Adana, Turkey between 20th of June 2020 and 19th of August 2020. Women were randomized into 4 groups: active TENS 1 (100 Hz and 100 mu s) (n = 14); active TENS 2 (80-100 Hz and 350 mu s) (n = 14); placebo group (n = 14); control group (n = 14). TENS therapy was initiated at the active phase of the first stage of labor, when cervical dilation was 4 cm, and administered for 30 min. Data were collected using the Personal Information Form, the Labor Monitoring Form, the Visual Analogue Scale (VAS), the State Anxiety Scale (STAI-S), and Biochemical Hormone Tests.Results: The participants in the active TENS 2 group demonstrated a significant increase in their oxytocin and endorphin levels (p<0.01) and a significant decrease in post-test plasma cortisol, labor pain perception, and anxiety levels (p<0.01) compared to active TENS 1, placebo, and control groups.Conclusions: High-frequency TENS application decreased labor pain perception and anxiety levels more significantly than stable frequency TENS, via effects on the release of oxytocin, endorphin and cortisol, which have positive contributions to labor.Trial registration: ClinicalTrials.gov.ID: NCT04851938 was registered on the 2nd of March 2020.