TENS is a drug-free kind of pain relief often used by women in early labour. TENS stands for Transcutaneous Electrical Nerve Stimulation. A maternity TENS machine consists of a battery-powered, hand-held controller connected by fine leads to four flat pads. It stimulates the release of endorphins & uses the gate theory of pain relief.
The TENS machine is really good to start in early labour to help you relax and find a rhythm with your contractions. When labour gets stronger and more regular you will probably find you will need other comfort measures like massage and shower/bath which means you may take it off then. Women from the yogababy classes have had great success using the TENS machine along with their breathing and active birth skills.