The TENS Machine - A Tiny Gadget with a Big Impact on Labor
I’m always surprised when I meet parents who haven’t heard about the tiny but mighty TENS machine for labor and birth. I just assume that everyone has heard about this brilliant little gadget but it’s slowly gaining popularity in the US as a comfort measure and a tool for shortening labor.
What Is a TENS Machine?
TENS stands for Transcutaneous Electronic Nerve Stimulation (quite a mouthful). A TENS machine is a small portable device that emits low-voltage currents used for pain relief in labor. (Don’t get hung up on the word voltage. You’re not tazing yourself). Stone carvings from as far back as 2500BC show fish that produce an electrical charge being used to reduce pain and Roman Emperor Claudius used ‘electric eels’ in a footbath to treat pain and improve blood circulation. Ouch!
How Does it Work?
Electrical stimulation is thought to stimulate nerve pathways in the spinal cord which block the transmission of pain and release pain relieving hormones. The skin is the largest organ of the body and the nerves in the transmit signals to the brain quicker than the slower signals coming from the uterus. It’s based on the gate control theory of pain control - According to the gate control theory, pain signals have to pass through ‘neurological gates’ at the spinal cord level and these gates determine whether the pain signals will reach the brain or not. So we feel pain when the gate is open so pain signals pass through and it is less intense or not at all perceived when the gate closes and prevents the signals passing through.
Have you ever banged your elbow – what’s the first thing you do (other than swear) you furiously rub it. By rubbing it you’re creating a competing stimulus that reaches the gate and closes it reducing your pain. So you can see how massage in labor, sterile water injections and using the bath/pool in labor can change how you experience pain in labor. You can read more about some of the different mechanisms of pain perception here and how you can alter them (very helpful to understand for labor).
How do I Use it in Labor?
You can use it right from the beginning in early labor.
Your partner will apply the 4 sticky patches from the TENS machine to your back just below the bra line and just at the underwear line (the above image shows the bottom patches a little high for my liking). It’s safe to use as long as you like in labor. Make sure you have extra patches and extra batteries. (Interestingly in the latest Chinese RCT they also placed the electrodes on acupressure points used for pain relief).
When it’s on the lowest setting it feels like a light ticking/tingling sensation on your skin. Then when you have a surge you press the boost button and it ramps up that stimulation….when the surge ends you press the boost button again to turn it off. As labor intensifies you turn up the baseline sensation and get a stronger ‘boost’ with each surge.
Sometimes when mom is in a very focused state I’ll control the TENS for her and she’ll signal me to boost and un-boost. In my experience if a mom finds the tingly sensation uncomfortable in early labor try it again later in active labor. It can be really helpful moms experiencing back labor and some of the earlier studies show high rates of satisfaction for coping with back labor (82%).
Important Note for Partners:
Sometimes mom can get so used to the TENS that she may feel it’s lost it’s magic…and she wants to take it off. Remember to turn off the unit before you remove the sticky patches and be ready to really quickly put it back on for the next surge when mom realizes it really was working for her. The TENS unit can’t be used in water so when your partner is getting out of the shower/bath be sure to DRY HER BACK PROPERLY! The sensations mom experiences from a wet TENS unit won’t win you any brownie points.
Where Can I Get one?
Labor TENS machines are available to purchase online on Amazon.co.uk (not on Amazon.com).
If you’re in Europe you can probably rent one for your due month.
Ask if your hospital has them available to use (but you’re limited to it’s use only after you’re admitted - having it at home might help you stay home longer).
Ask your doula/midwife if they offer a TENS machine loan as part of their services.
In some countries such as Brazil you may have to have it prescribed. Sometimes stores run special offers on generic TENs machines but only an obstetric TENS has the boost button for surges.
Sciencey Stuff
A 2011 Cochrane review included results from 17 studies with a total of 1466 women. Thirteen studies examined TENS applied to the back. Results show that pain scores were similar in women using TENS and in control groups. There was some evidence that women using TENS were less likely to rate their pain as severe but results weren’t consistent. But many women said they would be willing to use TENS again in a future labor.
A 2015 study published in Turkey shortened labor by about 2 hrs as well as reducing labor pain. TENS use was also associated with less opioid use in some smaller studies.
In some research it helped moms to manage around 7 hours longer before requesting medication compared to only 2 hours for moms not using the TENS. So if it’s important to you to reduce or eliminate the use of medication in labor this is a must have in your labor toolkit. The more tools you have the more in control you’ll feel. The evidence shows no negative side effects for mom or baby and it doesn’t interfere with hospital equipment.
in 2021 a randomized controlled trial reviewed the effects of the use of a TENS machine by during the first stage of labour in China. 326 women participated in the trial. The parents using the TENS had significantly lower pain scores in labor and after. Parents using the TENS also demonstrated a statistically significant shorter duration of the active labor.
Other Ways to Use a TENS
If you’re really unlucky sometimes when a mom gets an epidural she can be left with a ‘window’ of area where you’re still feeling pain. Usually with a bit of repositioning staff can fix it – but not always. If it’s really painful ask staff to call the anesthesiology to come – sometimes they need to re-site the epidural. Another option is to use the TENS machine on that window of skin – it can work beautifully as you get instant relief and may be sufficient for you so you don’t have to have the epidural re-sited.
Pregnancy Itch
A growing area of research to watch is the use of TENS for pregnancy itch especially cholestasis. One 2015 study for condition with severe itching including liver conditions suggests that this may be a safe therapy for moms in the future. If you have cholestasis and are trying to find ways to manage the horrible itch it might be worth talking to your careprovider about this option, very few obstetricians seem to know about this research.
Cesarean Incision Pain
A TENS machine may also be helpful for cesarean incision pain and healing (not on the incision…I repeat NOT ON THE INCISION). It can be applied around the area of your incision dressing). Several studies have shown an improvement in the rate of wound healing when electrodes have been applied locally around sacral and leg ulcers. It has been hypothesised that this could be due to TENS increasing blood flow to the area or by the release of brain endorphins. The most recent evidence is inconclusive but it’s an option for moms to try if they prefer not to take a lot of medication after a cesarean especially given the concerns about using opioids after a cesarean. Talk to your careprovider or nurse about using the TENS machine in this way.
Are There Any Contraindications?
Some moms have skin sensitivity to the sticky patches so it’s a good idea to test one out on your skin before labor.
If you have a pacemaker or any electronic implanted device a TENS machine isn’t recommended.
If you have epilepsy - talk to your careprovider about the safety of using a TENS machine.
Do not use in water.
For more information watch Sabine’s video
Did you use a TENS machine? Did you love it or hate it?
