If you're the sort of person who likes to know the 'how' behind how something works, then read our explanation of how TENS works to block pain through the pain gate theory.
The gate control theory of pain suggests that our perception of pain is not just the result of a straightforward signal from our nerves to the brain, but is instead modulated by a "gate" mechanism in the spinal cord. This "gate" can either allow or block pain signals before they reach the brain.
If the gate is open, pain signals pass through and are sent to the brain, where they are perceived as pain.
If the gate is closed, pain signals are blocked and do not reach the brain, reducing the perception of pain.
During labour, your body sends pain signals from your uterus to your brain through nerves. These pain signals are intense.
A TENS (Transcutaneous Electrical Nerve Stimulation) machine is used by placing 4 sticky pads on your lower back. This area is chosen because it’s a key site where pain signals from the uterus pass through the spinal cord.
The TENS machine generates small (safe) electrical impulses that travel through the skin and stimulate the nerves. The impulses feel like a pleasant pulsing sensation.
These electrical impulses stimulate the sensory nerve fibres, particularly the large A-beta fibres, which are responsible for transmitting non-painful sensations like touch and pressure.
According to the gate control theory, stimulating these large nerve fibres helps to "close the gate" in the spinal cord. The gate is a figurative way of describing how the spinal cord controls the flow of pain signals to the brain. When the gate is closed, fewer pain signals from the smaller pain-carrying nerve fibres can pass through.
With the gate closed, the number of pain signals reaching the brain is reduced. This results in a decreased perception of pain.
In addition, the TENS machine also promotes the release of endorphins, the body's natural painkillers, which further helps in pain relief. When using a TENS, it’s important to give your body time to build up these endorphins so you should put the TENS on early in labour.
As your labour progresses and the contractions increase in intensity, you can control the strength of the electrical impulses, allowing you to manage your pain more effectively.
In summary, a TENS machine helps reduce pain by stimulating nerve fibres that close the gate in the spinal cord, thereby blocking pain signals and reducing the perception of pain, as well as increasing the release of endorphins.