A TENS device is a small handheld device with wires coming out of it attached to electrodes in pads that you stick to your skin. TENS stands for transcutaneous electrical nerve stimulation. TENS units or machines are commonly used in patients who suffer from chronic pain. A TENS machine works by sending electrical nerve stimulation through low voltage electrical impulses through the electrodes on your lower back. Women in labor first used these devices in the 1970s. Today these devices are standard for use during labor in the United Kingdom. The big question is, does a TENS machine make a difference in labor? This episode examines the pros and cons of TENS machines and digs into the research and evidence available on their use.