What is TENS and how does it work?

TENS stands for Transcutaneous Electrical Nerve Stimulation. It’s a small, battery-operated device that sends gentle electrical pulses through four sticky electrode pads placed on your lower back during labour.

It might sound a little technical, but the science behind TENS is actually quite simple. It works in two clever ways to help your body cope with labour pain — without drugs, needles, or limiting your movement.

1. TENS helps reduce pain signals to the brain

The main way TENS works is by changing how your brain perceives pain.

The electrical pulses from the machine stimulate the sensory nerves in your lower back — particularly the nerves responsible for touch and pressure. According to something called the Gate Control Theory of Pain, these sensory signals can help reduce the number of pain signals able to travel to the brain.

Think of it like this: your nervous system can only process a certain amount of sensory information at once. The rhythmic buzzing or pulsing sensation from the TENS machine helps ‘flood’ the nervous system, so contraction pain signals become less dominant and harder for the brain to focus on.

In simple terms, the TENS sensation competes with contraction sensations — reducing how strongly pain is perceived.

2. TENS stimulates the release of endorphins

Endorphins are your body’s own natural pain-relieving hormones and they help reduce your perception of pain while also promoting feelings of calm, wellbeing, and control during labour. They’re often described as the body’s ‘natural morphine’ because they help raise your pain threshold and support your body through physically intense experiences like childbirth.

The boost button: what makes an obstetric TENS different

One of the key features of an Obstetric TENS machine is the boost button, which allows you to move between two different intensity levels during labour.

During strong contractions, you can press the boost button to increase the intensity of the pulses. This stronger stimulation activates the sensory nerves, helping to reduce the transmission of pain signals from the uterus through the spine and to the brain.

Between contractions, you can return to a lower, steady setting. This gentler level is often used to promote the body’s natural release of endorphins, helping you stay relaxed and rested between waves.

This ability to simply press one button to adjust between the two settings instantly is what makes obstetric TENS unique.

Why women love using TENS during labour

TENS machines are recommended by midwives, they’re 100% safe for mum and baby, and they can be used for support in early labour at home.

For many women, TENS is an empowering tool that helps them feel calmer, more focused, and more in control — which in turn supports the body’s ability to labour efficiently. When fear and tension are reduced, it helps the body work more effectively with oxytocin, the hormone that drives labour.

For many women, TENS helps them work with their contractions rather than feeling overwhelmed by them.