A review of the effect of TENS for pain relief in labour was conducted by researchers in the Cochrane Collaboration. After searching for all relevant studies, they found 19 studies done by other researchers. Their findings are summarised below.
Why TENS for pain relief during labour?
Pain during labour is described as a complex phenomenon. The experience of pain involves physiological, cognitive and psychological factors and varies greatly from one woman to another.
Transcutaneous nerve stimulation (TENS) is used to relieve pain for different, both acute and chronic, conditions. It has been used for pain relief during labour since the 1970s.
TENS consists of a hand-held device connected to electrodes which are attached to the skin. Through these electrodes, mild electric pulses are sent along your nerves to the spinal cord and the brain. When using TENS, women experience a tingling sensation around the site of the electrodes. There are different theories on how TENS relieves pain, but there is still uncertainty about the precise mechanisms of pain relief and TENS.
When TENS is used for pain relief during labour, the electrodes are applied to the lower back, to acupuncture points or applied to the cranium. Most commonly TENS is applied to the back. The women can operate the TENS unit themselves, by regulating the intensity of the impulses during painful contractions. There is evidence that TENS is a popular method for reducing pain in labour, but there is uncertainty whether this is because TENS actually relieves pain efficiently, or whether this is because it helps to take away the women’s focus on the pain and increase their sense of control during labour.
TENS as an intervention does not seem to have serious adverse effects on the women or their babies, but there may some local skin irritation to the areas where the electrodes were applied.
What does the research say?
Not all research provides the same quality of evidence. The higher the quality, the more certain we are about what the research says about an effect. The words will (high quality evidence), probably (moderate quality evidence) ormay (low quality evidence) describe how certain we are about the effect.
The studies showed that using TENS to acupuncture points:
- probably reduces the number of women with severe pain during labour
- probably increases the number of women satisfied with pain relief during labour
- may increase the number of women who would use TENS again in future labour
- may make little or no difference to the caesarean section rate
The studies showed that using TENS to the lower back:
- probably makes little or no difference to the number of women satisfied with pain relief during labour
- may increase the number of women who would use TENS again in future labour
- may make little or no difference to the caesarean section rate
Tables of Results
What Was Measured | Placebo | TENS To Acupuncture Points | Quality Of Evidence |
|---|---|---|---|
| Severe pain during labour | 85 per 100 | 35 per 100 (27 to 47 per 100)1 | Moderate |
| Women satisfied with pain relief | 17 per 100 | 68 per 100 (30 to 100 per 100)1 | Moderate |
| Women would use TENS again in future labour | 66 per 100 | 96 per 100 (78 to 100 per 100)1 | Low |
| Caesarean section rate | 4 per 100 | 6 per 100 (1 to 34 per 100)1 | Low |
1 The numbers in the brackets show the range in which the actual effect could be.
What Was Measured | Placebo | TENS To Lower Back | Quality Of Evidence |
|---|---|---|---|
| Severe pain during labour | We are uncertain because the quality of the evidence is very low | ||
| Women satisfied with pain relief | 26 per 100 | 34 per 100 (26 to 42 per 100)1 | Moderate |
| Women would use TENS again in future labour | 41 per 100 | 63 per 100 (53 to 73 per 100)1 | Low |
| Caesarean section rate | 6 per 100 | 8 per 100 (5 to 13 per 100)1 | Low |
1 The numbers in the brackets show the range in which the actual effect could be.
Where does this information come from?
The Cochrane Collaboration is an independent global network of volunteers, dedicated to summarizing research about health care.
This information is taken from this Cochrane Review: 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.
This summary was prepared by:
Elin Strømme Nilsen and Vigdis Underland, the Nordic Cochrane Centre’s Norwegian branch, Norwegian Knowledge Centre for Health Services, on behalf of the Cochrane Complementary and Alternative Medicine Field, and with funding from the US National Center for Complementary and Alternative Medicine (NCCAM) of the US National Institutes of Health (grants number R24 AT001293).
Appendix 3.c.
TENS to acupuncture points compared to placebo TENS for pain relief during labour
Patient or population:pain relief during labour
Intervention: TENS to acu points
Comparison: placebo TENS
Outcomes | Illustrative Comparative Risks* (95% CI) | Relative Effect | No Of Participants | Quality Of The Evidence | |
|---|---|---|---|---|---|
Assumed Risk | Corresponding Risk | ||||
| Severe pain during labour | 85 per 100 | 35 per 100 (27 to 47) | RR 0.41 (0.32 to 0.55) | 190 (2 studies2) | moderate1 |
| Women satisfied with pain relief | 17 per 100 | 68 per 100 (30 to 100) | RR 4.10 (1.81 to 9.29) | 90 (1 study4) | moderate 3 |
| Women would use TENS again in a future labour | 66 per 100 | 96 per 100 (78 to 100) | RR 1.45 (1.18 to 1.79) | 100 (1 study6) | low1,5 |
| Caesarean section rate | 4 per 100 | 6 per 100 (1 to 34) | RR 1.50 (0.26 to 8.6) | 100 (1 study8) | low1,7 |
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. Thecorresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio
GRADE Working Group Grades of Evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.
1 Chao 2007: Uncertainty of randomisation procedure, allocation concealment and blinding. Results relating to pain were difficult to interpret. Wang 2007: Uncertainty of randomisation procedure and allocation concealment, no blinding.
2 Analysis 1.1.2: Wang 2007, Chao 2007.
3 Wide CI.
4 Analysis 1.3.2: Wang 2007
5 Only one small trial with a total of 100 participants.
6 Analysis 1.4.2: Chao 2007.
7 Wide CI, CI crosses no difference.
8 Analysis 1.5.2: Chao 2007