Inclusion Criteria:  Singleton pregnancy Between ages 18-39 years Vertex presentation Speak, read and understand Danish At term (37-42 weeks gestation age)  Exclusion Criteria:  High-risk pregnancies (including risk factors: eclampsia, pre-eclampsia, diabetes, gestational diabetes, hypertension, and hypotension, intrauterine growth restriction, polyhydramnios, and oligohydramnios). Pre-gestational body mass index above 40 kg/m2 Use of fetal-scalp electrode during the experiment Use of pacemakers and other electronic implants Severe arrhythmia Present musculoskeletal/neurological illnesses Chronic pain within last 6 months Present medicated mental disorders Dermatological disorders Use of other long-acting pain relief Use of TENS 48 hours before the trial Drug addiction defines as the use of cannabis, opioids, or other drugs. Smokers Lack of ability to cooperate