I am fascinated by the popularity of using transcutaneous electrical nerve stimulation (TENS) devices during labour. This handy little piece of technology arrived on the maternity scene many years ago, and is now particularly entrenched in Britain (it may have been introduced into other countries but has not taken hold there with the same enthusiasm). How has is become so popular, when there is no evidence of its efficacy, it promotes a reliance on technology and costs money? Clever marketing, for a start!
Pregnant women are exposed to the promotion of TENS everywhere they go: the baby magazines, Boots Chemists, pre-natal class handouts and pregnancy books all carry information and frequently glossy ads for this increasingly ubiquitous device. Even the National Childbirth Trust hires them out and I know of several independent midwives who offer them to clients as part of their package. It seems that women and their midwives have taken to TENS with gusto, and whilst this may be the hallmark of a successful product launch, as an example of the selling of unnecessary technology the way it was achieved deserves closer scrutiny.
The entrenchment of TENS for use during labour is a wonderful example of how a vulnerable population can be hooked into “quick fix” remedies that are primarily designed to make money for a manufacturer. Given that there were no preliminary studies to investigate its efficacy and safety in labour, and no subsequent evidence that it actually works as claimed, the sales success of this product must be the result of a carefully thought out marketing strategy, which will probably have included some of the following steps:
First, start with a device that has some proven benefits in relieving chronic back pain due to disease or functional disability. It will need to have been widely accepted by the medical experts for this purpose and have produced testamonials from satisfied clients that can be used to sway sceptics and to bolster the advertising in new markets.
Having achieved success in this initial area of health care, look around for opportunities for diversification – are there any other areas where the device could be promoted, preferably with the potential for many sales? Are there other conditions that involve pain, affect a large segment of the population and involve a group that is willing to spend money? Yes – labouring women! Here is a condition that fits these criteria magnificently, a group who are already feeling very anxious about pain in labour, who are devoted to doing the best for their unborn babies and are willing to spend money on t he special event of pregnancy
Next, bring in the marketing people to develop strategies for effective promotion, and therefore sales. Their advice may include the suggestion to focus on the supposed benefits of this device for easing the “suffering” of women giving birth and the fact that women can avoid exposing their unborn baby to potentially risky medications. They may even suggest that TENS enhances the physiological process by raising endorphin levels, thus making a natural birth “more likely”. A bit of clever spin that plays on the “no need to suffer” angle while apparently doing good things for yourself and your baby will do the trick!
One very effective way to increase sales will be to have some authoritative endorsements from appropriate people and organisations. A few celebrities or high profile names will do wonders for profit margins and if it is possible to give them a percentage of sales in return for their “words of wisdom” this will ensure they stay loyal to the product and continue to promote it for their own gains. Finally, design an array of sensitive advertising material – plenty of quasi-scientific hype will be necessary to make the gadget sound as “non-medical” and “ecological” as possible.
These approaches certainly seem to be working well – women are buying or hiring the gadgets and midwives are enthusiastically endorsing them. The manufacturers must be very pleased with their bottom line as well. So why am I challenging this apparently useful product? For me, there are basic questions that need to be answered about TENS ( and for other birth technologies): do women really benefit from using TENS? Is it all it is claimed to be? What are the implications of generating reliance on technology for dealing with labour pain instead of supporting women’s innate capabilities?
My starting point will be the evidence, since this is what women are encouraged to use as a basis for their decisions and midwives should use as a basis for their practice. The Cochrane Library has reviewed the randomised trials that have investigated TENS 1 The findings state: “No study recorded any difference in pain intensity or relief scores between TENS and control during labour”. In assessing the implications of the review, the authors state “…. in practice, women should be offered more effective interventions for the relief of pain in labour… and that no further money should be spent on researching TENS in labour”. A more recent review reached similar conclusions 4.
What about the claim that TENS increases endorphin levels and therefore is useful in encouraging natural birth? I have not seen any research that shows TENS increasing endorphin levels in labour. There may be some evidence of increased endorphin levels when TENS is used in other situations (but I haven’t found that either), but it any case, it would be unwise to assume from any such studies, that a similar effect would occur in labour, given that birth is a completely different physiological condition.
Midwives have told me “that it is safe to use and is harmless”. This is an interesting concept – if it is harmless then it can be having no impact or effect at all, so why are women relying on it for easing pain in labour? The makers claim that it works by “occupying” the nerve fibres in the lower back that are carrying the pain messages to the brain (the “gate control theory” 2,3) thus blocking the transmission of pain signals from the uterine nerves which are lower down. If this was in fact working, then TENS would surely eliminate the sensation of labour pain either completely or at least significantly, perhaps enough to enable to woman to avoid the need for other pain relievers, especially medications. The evidence suggests that women do not use TENS instead of epidurals or opiate drugs, but as an addition – TENS is often used until the epidural arrives or the pethidine is given.
There are women who report that “the TENS got me through” labour. The Cochrane Library review shows that TENS had the same degree of effectiveness as a placebo. Is this such a bad thing? I believe that women should take the credit themselves for weathering labour and dealing well with the pain they encounter. Why give a gadget the kudos when it was playing a sham role? We can’t afford to undermine women’s confidence in themselves during labour any further – it is at an all-time low as it is.
There are other reasons for concern as well: the impact of TENS (and medications) on wider community attitudes to labour and its necessary pain; the deliberate exploitation of women’s fears and anxieties; the co-option of organisations that should be promoting women as strong and capable to a campaign that highlights women’s apparent weaknesses, and the commercial imperative that has once again scored at the expense of women and made money through dubious claims (snake oil salesmen of the 21st century?).
If TENS can be sold so effectively from such a shaky scientific base, then we must we wary of other campaigns that focus on selling other unnecessary technologies and gadgetry for labour. I believe that these are important issues that need discussion in professional circles, by organisational decision-makers, and with expectant parents in pre-natal programs.
This article first appeared in “the Practising Midwife” Vol 6 No 2. February 2003.
1. Carroll D, Moore R A, Tramer M R, McQuay H J. Transcutaneous electrical nerve stimulation does not relieve labor pain: updated systematic review.Contemporary Reviews in Obstetrics and Gynecology1997, , 195-205.
2. Seigel, D. The gate-control theory. American Journal of Nursing 74:498, 1974.
3. Bonica, J. et al, Altering the Experience of Pain. New York: Pfizer Laboratories, 1979
4. Dowswell T, Bedwell C, Lavender T, Neilson JP. Transcutaneous electrical nerve stimulation (TENS) for pain relief in labour. Cochrane Database of Systematic Reviews 2009, Issue 2. Art. No.: CD007214. DOI: 10.1002/14651858.CD007214.pub2.
Published in The Practising Midwife Vol 6, No 2, Feb 2003