Transcutaneous Electrical Nerve Stimulation (TENS) for Pain Relief During Labour
A TENS machine is a way of managing pain without drugs. It uses electrical pulses and the theories of Gate Control and Diffuse Noxious Inhibitory Control; both of which changes the way the brain perceives pain. TENS machines are easily available and consist of a hand-held device connected to electrodes that work through pads placed on the body. Through the electrodes, electrical pulses are sent through the spinal cord and into the brain. Researchers think that TENS works by changing how a person perceives their pain.
The machine allows you to control the intensity of the pulses and TENS therapy can be stopped at any time without any residual effects. It can be used anywhere, just not in water. To use TENS machine for childbirth it is best to use a unit specifically designed for labour pain.
TENS units have been used since the 1970s to relieve pain for a variety of conditions such as menstrual pain, arthritis, and other chronic pain conditions. The FDA has also approved it for use in treating post-surgery and traumatic pain. TENS is used all over the world, but it is important for you to find out if your preferred hospital or midwife has units available for you to use, or if you need to provide your own unit. The Perfect MamaTENS is a great option if you would like to invest in your own unit.
Low-Intensity TENS & Gate Control Theory
The first theory on how TENS works involves when it is used on the lower settings and involves what is called Gate Control Theory. This theory works on the idea that only a certain amount of stimuli can get through to the brain. The idea of a gateway means that if you flood the brain with sensory information the gateway manages signals so the brain doesn’t register the pain as clearly.
High-Intensity TENS & Diffuse Noxious Inhibitory Control
But scientists believe the mechanism changes when the intensity is increased. The thoughts behind Diffuse Noxious Inhibitory Control theory is that by stimulating the body with another source of pain, the body is triggered to release its natural defense of pain-relieving hormones called endorphins. It tricks the brain to create its own pain relief.
Researchers also think that TENS during labour might work by decreasing anxiety, making you feel like you have more control over your labour, and by providing a distraction from contractions.
How to Choose a TENS Unit
There are different types of TENS units available and it is best to choose one specifically made to deal with labour pain. Mothers tend to like units with larger pads as labour pain can be spread out, and some (like the Perfect MamaTENS) have a boost button which is useful to push during a contraction.
A TENS machine can be purchased anywhere and doesn’t require special training. Some studies have shown that when a trained acupuncturist applied the pads to acupuncture points it increased the unit’s performance.
Research on TENS & Labour pain
Much of the research on TENS and labour pain management has been done since 2011. Here are summaries of four of the biggest studies:
Dowswell et al. (2011) Cochrane Review
This review involved 17 randomized controlled trials with a total of about 1,500 participants. The groups were broken down into three with one using routine care, one using a placebo TENS (where pads were applied but the unit was not turned on or only on a low intensity), and the last compared TENS to other non-drug pain relief methods. There are some concerns that the subjects became aware that their unit was not turned on and so damaged the results of placebo trials.
The study found that there was not much difference in pain levels reported between people who used TENS and the control group. But they found that when people applied TENS to acupuncture points, they rated their pain less severely than the control group.
Interestingly people in both the TENS group and placebo TENS group were more likely to say they’d use the method in the future. It may be that having a TENS unit gave the mothers a distraction and a sense of control.
Shahoei et al. (2017)
A study in Iran used a randomized controlled trial where 90 first-time mothers were assigned either a low intensity TENS, a placebo TENS, or routine care. The treatment was started at about four-centimeter dilation and continued until birth.
After the first hour, there was not much of a difference in pain scores across all three groups, but at two, three, and four hours significant differences in pain levels were reported. During the pushing stage of labour only 20% of the people in the TENS group reported severe pain compared to about 83% – 87% of mothers in the other two groups.
Four hours after birth only 7% of the mothers in the TENS group recalled severe pain whereas 43% of those in the placebo group and 60% of the standard care group remembered their pain as severe.
Santana et al. (2016)
Researchers in Brazil held a randomized trial where 46 first-time mothers were assigned to either TENS or standard care. In the TENS group treatment was started when the patient reached about four centimeters dilation. The treatment consisted of placing the pads on the back area for 30 minutes. Then asking the mother to report her pain levels.
Before the application of TENS 70% of participants in both groups reported their pain to be a seven or higher on a one to ten pain scale. Of those who received TENS treatment only 34% said their pain was a seven or higher compared to 83% of mothers in the standard care group.
It was also found that those randomly assigned to receive TENS treatment were found to wait about seven hours before they requested additional pain relief, compared to only two hours in the standard care group. This study found no differences in reports of maternal satisfaction with TENS or no TENS.
Shaban et al. (2013)
In 2013, researchers in Egypt randomly assigned 100 mothers in active labour to receive either low-intensity TENS applied to the back until the participants reached 10 centimeters dilation or an injection of the narcotic Pethidine/Demerol.
Both groups reported decreases in pain with no significant difference between them. At 48 hours after the birth, 83% of the TENS group participants were satisfied with their experience compared to 10% of the other group. The Demerol group also reported side effects including drowsiness, nausea, and vomiting. Babies in the Demerol group also had lower Apgar scores. The TENS group reported no side effects.
Though more research needs to be done, the results seen so far are promising, especially in regards to TENS users listing no side effects. The current evidence points to TENS as a useful option for pain management during labour.
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