Acupuncture Treatment of Labour Pain

Physiology of Pain and Critical Analysis of Research

Jimi Windmills

Introduction

This report will examine the use of acupuncture to treat labour pain. I will first look at the physiology and mechanisms of labour pain from a western perspective, and the options for conventional treatment of labour pain. Labour pain was not considered a pathology in China until the 1970's and thus was never treated with acupuncture. Therefore, the explanation of the mechanisms of labour pain from a TCM perspective will be necessarily short. I will briefly look at some acupuncture treatment protocols for reducing labour pain that have been developed since the 1970's. Following this, there will be a critical analysis two clinical trials investigating the efficacy of acupuncture as an analgesic in the management of labour pain.

Western Physiology of Labour Pain

According to Rowlands and Permezel, pain is caused by either tissue damage (inflammation) or nerve damage (neuropathic). When tissue is injured, an array of chemical mediators are released, including noradrenaline, hydrogen ions, potassium ions, bradykinin, prostaglandins, histamine, purines, cytokines, nerve growth factor, 5-hydroxytryptamine, leukotrienes and neuropeptides. These mediators stimulate the small A delta and C afferent fibres which act as receptors for nociception from skin and subcutaneous tissue superficially, and deeper structures such as muscle, fascia and organs (Rowlands and Permezel 1998: 348). The cerebral cortex plays a minimal role in pain perception. It is involved in the emotional and behavioural response to pain, by associating the pain of labour with, for example, past experiences, emotions, personality and ethnic, social and cultural background (Rowlands and Permezel 1998: 349).

First Stage

During the first stage of labour, pain is mostly associated with physical distension of the lower segment of the uterus, along with dilation of the cervix, and other associated muscle contractions. These uterine mechanics result in excitation of nociceptive afferents. The severity of the pain increases with the duration and intensity of contractions.

The uterus and cervix are supplied by unmyelinated, slow conducting, C fibres, which travel to the posterior nerve roots of the 10th, 11th and 12th thoracic and 1st lumbar nerves, to the interneurones in the dorsal horn. Pain from contractions is transmitted slowly and is poorly localised. Pain is referred to the dermatomes supplied by T10, T11, T12, and L1. Early in the first stage, this is experienced as a dull ache over the area supplied by T11 and T12, which becomes increasingly severe as labour progresses, and the area of referred pain expands to include the areas supplied by T10 and L1, the abdomen, lower lumbar and upper sacrum (Rowlands and Permezel 1998: 350-1).

Second Stage

In the second stage of labour, distension of the uterus and cervix continue. Pain is distributed similarly to the first stage, however, the pressure on the pelvis is increased by the baby. Pain during the second stage is often described as sharp and localised in the perineum, anus, and rectum, and can also refer to the thighs. This pain comes from the pressure exerted on the uterine ligaments, parietal peritoneum, fascia and muscles of the pelvic floor, urethra, bladder, lumbosacral plexus and rectum. Nerve pain is caused by direct pressure on the lumbosacral plexus. Distension of the vagina and perineum stimulates the pudendal nerve derived from S2, S3 and S4. Impulses travel first to the dorsal horn then to the brain along the spinothalamic tract, via fine, myelinated rapidly transmitting A delta fibres (Rowlands and Permezel 1998: 352).

Assessment

Assessment of labour pain is usually carried out by the midwife attending the birth. This assessment is very much based on the subjective experience of the midwife, and how well she thinks the mother is coping with the experience. According to Baker et al., this often leads to pain being under or over-estimated (Baker et al. 2001: 171). With the growing rise in the use of EDA's some research is being done on effective ways to get a more accurate assessment of the mothers pain. In labour pain research, one of the tools that is often used to assess pain is a visual analogue scale (VAS). Visual analogue scale is a 100mm line, often coloured yellow at one end, marked with “no pain”, and transitions through orange to red at the other end, where its marked, “most intense pain imaginable”. The mother is asked how far along the scale she would rate her current pain experience. The distance to this point is measured from the “no pain” end of the scale, and is converted into a pain score. A score of 5.7 for example, is a mid-range score, marked 57mm along the 100mm line.

Treatment

Western medicine strives to provide a painless route to birthing. Interestingly, this drive to medicate the pain seems to have increased in parallel with the use of synthetic oxytocin. Synthetic oxytocin, is used to induce labour, and also to intensify contractions to speed up the dilation of the cervix. The contractions generally become so painful under the influence of synthetic oxytocin that pain relief becomes absolutely necessary, and in many cases this mean an epidural anaesthesia (EDA) (Gaskin 2003).

The most frequently used pain medications are intramuscular or intravenous opiates (usually pethidine), or inhaled nitrous oxide (NO2). However, the pain relief from NO2 seems to have more to do with its dissociative properties than any function as a true analgesic. Other interventions include sterile water injection, and hot baths. Today, epidural/spinal anaesthesia is becoming more common, with some hospitals claiming that 80-90% of their mothers “choose” this method.

TCM Perspective

On the issue of the traditional use of acupuncture to treat labour pain in China, there are conflicting views. Some argue that acupuncture was not used to treat labour pain in China until the 1970s. According to Maciocia, in old Chinese culture, pain during labour was expected. They talked about sensations that accompanied labour and contractions, but not about pain. Therefore, there were no points prescribed to treat pain associated with a normal vaginal birth (Maciocia 1999: 560). This argument for the relatively recent development of using acupuncture for pain relief in labour is supported by Ma et al. who states that 'acupuncture has been used in China for more than 3000 years. The use of acupuncture for decreasing labour pain […] was introduced in the 1970s' (Ma et al. 2010: S14). This is in contrast to the opinion of MacKenzie et al., who states in the introduction of their study that 'Acupuncture has been used for pain relief in labour for centuries in China' (MacKenzie et al. 2011: 440).

In the 1950s the idea that labour pain was pathological and therefore something to be treated emerged (Gaskin 2003). This led to the development of a number of pharmacological and procedural interventions. In the 1970s, there was a new found interest in acupuncture in the West. This, combined with the medicalised view of labour and delivery, saw the beginning of trials in the use of acupuncture as an analgesic in the management of labour pain during childbirth. According to Maciocia, the first reported delivery using acupuncture as an analgesic was performed by Christman Ehrström in Stockholm, Sweden, 1972. This was followed in 1974 by a series of 20 deliveries in France using electro-acupuncture (Maciocia, 1999: 560). Auricular acupuncture has come to be seen as a better choice for analgesia, since it does not restrict the movement of the mother (Maciocia 1999: 563; West 2008: 195).

Labour in TCM begins with a shift from a pattern of Yin accumulation to one of Yang movement. This shift progresses gradually, culminating in Yang expelling Yin (Betts 2006; Maciocia 1999; West 2008). 'Qi pushes Blood and the uterine door opens in a significant downward movement' (Maciocia 1999: 561).

Maciocia (1999: 565-6) identifies one, and Betts (2006: 177-8) identifies two specific patterns involving increased levels of pain. That is, pain that is more intense than would be expected for the normal 'sensations' that go hand in hand with the contractions of an uncomplicated, naturally progressing labour.

West takes a different approach to treatment of pain during labour. While west identifies four patterns of disharmony in labour, her point prescription is not tailored accordingly. West treats specifically for pain associated with normal labour, and begins treatment with preselected points as early as possible in the labour. Ear points are chosen to stimulate contractions and provide analgesia. Uterus point and Endocrine point for contractions and Shenmen for general analgesia or the Bladder point if there is lower back pain. Insert the needles as early as possible in labour, and tape them in place so they can be used throughout the labour with electro stimulation. It is necessary to apply electro stimulation for between 30 – 40 minutes to achieve a therapeutic effect. This is particularly useful when labour is induced artificially, as artificially stimulated contractions do not allow the body to naturally build-up of endorphins. To maintain freedom of movement for the mother use a pocket sized electro-stimulator that can be attached to the mothers clothing. Body points can be used to great effect if the mother is in a position to be able to access them. Pain can be treated with the points BL-31, BL-32, L.I.-4, and LIV-3 (West 2008: 195-8).

Prognosis

The prognosis of labour pain is good. Generally speaking it is a self limiting condition that spontaneously resolves of its own accord between 6 to 24 hours after onset. In some circumstances (more popular in recent years) some form of medical intervention is utilised. However, according to Gaskin, these interventions in most cases are unnecessary, and only interfere with the labour process, and in some cases have resulted in morbidity and or mortality to the mother or child (Gaskin 2003).

Critical Analysis

Research articles were gathered from various databases and journals using the following search terms; Acupuncture, Labour, Labor, Pain, Birth, Delivery, Treatment, Management. The following Databases and Journals were searched:

• The Journal of Chinese Medicine
• American Journal of Obstetrics and Gynecology
• EBSCO
• Science Direct
• Natural Standard
• PubMed
• ProQuest
• Cochrane Library

The search resulted in six systematic reviews, and seven randomised controlled trials. Most of the RCT's are of fair quality, and before I start my critical analyses of my chosen papers, I would particularly like to draw attention to research conducted in Iran in 2007. This was a high powered, single blinded RCT involving 150 participants, which among other outcomes, concluded that acupuncture could decrease the active phase of labour and reduce the amount of synthetic oxytocin needed for augmentation (Hantoushzadeh et al. 2007).

STUDY 1

Borup, L, Wurlitzer, W, Hedegaard, M, Kesmodel US, Hvidman, L 2009, 'Acupuncture as Pain Relief During Delivery: A Randomized Controlled Trial', BIRTH, vol. 36, pp. 5-12, Viewed 4 September 2012, <http://www.ebscohost.com>.

Objective

'To compare the effect of acupuncture with transcutaneous electric nerve stimulation (TENS) and traditional analgesics for pain relief and relaxation during delivery with respect to pain intensity, birth experience, and obstetric outcome' (Borup et al. 2009).

Setting

The study took place in the delivery ward of the Aarhus University hospital in Skejby, Denmark. Conducted between march 2001 and feb 2004. The delivery ward in this hospital see about 4,500 – 4,800 deliveries annually.

Funding

The study was jointly sponsored by the 'Aase and Ejnar Danielsen’s Foundation, Kgs. Lyngby, Denmark; Knowledge and Research Center for Alternative Medicine, Aarhus, Denmark; Sophus Jacobsen Foundation, Copenhagen, Denmark; The Danish Midwifery Organisation, Copenhagen, Denmark; Lundbeck Foundation, Copenhagen, Denmark; Mads Clausens Foundation, Nordborg, Denmark; Hede Nielsen Foundation, Horsens, Denmark; The Research Fund at Aarhus University Hospital, Aarhus, Denmark; Else and Mogens Wedell-Wedellsborgs Foundation, Copenhagen, Denmark; and Copenhagen, Denmark; and King Christian the 10th Foundation' (Borup et al. 2009)

Inclusion / Exclusion Criteria

The study included healthy Danish speaking women in labour with a normal singleton pregnancy who were giving birth at term (37-42 weeks) and with a foetus in cephalic presentation.

The study excluded women with medical diseases, complicated pregnancies, and woman who had already received analgesics during labour.

Power Calculation

A power calculation was used to determine the number of participants needed. It calculated that 198 women were needed in the acupuncture group, with 198 women split between the two control groups. Taking into account a potential drop-out rate of one third, 600 women were needed in total. 607 women were initially randomised to the study, and of those 517 completed the treatment. 490 of these woman completed the follow-up questionnaire, which makes this one of the biggest studies performed on acupuncture and labour pain to that date.

Recruitment, Randomisation and Blinding

This study was performed as a randomised controlled trial with no blinding. Women in labour who requested pain relief were asked to take part in the study. If they consented, they were randomised to receive acupuncture, TENS, or traditional analgesics, at a ratio of 2:1:1 by a computer-controlled randomisation system.

Groups

This study compared acupuncture to two control groups, one of which received TENS, the other received traditional analgesics. The women in the traditional analgesics group could request any form of traditional pain relief, from sterile water papules, nitrous oxide, warm bath, pethidine, and epidural analgesia (EDA). For each group, pain treatment began immediately after randomisation.

Dropouts

There was no significant difference between the 90 women that dropped out of the study and those that completed it, with respect to age, onset of delivery, mean cervical dilation, pain score at randomisation, induction of labour, postpartum haemorrhage, apgar score, umbilical pH. However there was a statistical difference in duration of labour (289 vs 365min), use of pethidine (1.7% vs 5.6%) and EDA (15.7% vs 30.0%).

Follow up Questionnaire

Participants completed follow-up questionnaires two months post-partum. These asked 14 questions about their birthing experience, satisfaction, pain relief, and possible side effects of the analgesic used.

Practitioner

Acupuncture was given by midwives who were trained in acupuncture and TENS. These midwives cared for all participants in all groups. Fifty midwives were certified after a 5-day course in western techniques of obstetric acupuncture and had at least six months clinical training using acupuncture during labour.

Diagnosis of Individual Patterns / Prescription of Points / Treatment

Acupuncture treatment was individualised depending on mobility and localisation of pain. The points used in each case were selected from a group of 34 predetermined points that had been use in the pilot study, and previous studies conducted in other countries. The points were GB20 + SiShenCong, BL-23, 24, 25, 26, 31, 32, 33, 34, 36, 60, YinTang, L.I.-4 10, 11, PC-6, HT-7, LU-7, SP-6, 9, GB-34, ST-36, NeiMa, LIV3, and Ear points Uterus, Endocrine, and ShenMen.

Needles used were 0.20x15mm, 0.30x30mm, and 0.35x50mm. Retention time of the needles was from 30 minutes to 2 hours, and could be repeated. Needles were removed if the woman became uncomfortable or in the case of obstetric pathology.

Outcome Measurements and Results

Primary outcomes were the need for pharmacological or invasive methods, level of pain assessed by a visual analogue scale (VAS), birth experience, and satisfaction with delivery, and pain relief evaluated at 2 months post-partum. Secondary obstetric outcomes were duration of labour, use of synthetic oxytocin, mode of delivery, post-partum haemorrhage, Apgar score, and umbilical cord pH value

Significantly fewer woman in the acupuncture group were treated with nitrous oxide, pethidine or sterile water papules compared to the traditional analgesic group, and fewer chose sterile water papules compared with the TENS group. A non-significant trend showed fewer woman having EDA's than in the traditional group. Significantly fewer women in the acupuncture group used pharmacological or invasive pain relief, or both, compared to the other groups. No significant difference was found in the pain scores between the three groups at any point during labour.

Overall quality and Level of Evidence

This study is of fair quality, and scores 3 on the Jadad scale. It was randomised, and done so appropriately, and clearly details the drop outs. However it was not double (or even single) blinded.

 

As an RCT it provides a good level of evidence. However, without being a double-blinded placebo controlled RCT, it does not reach the gold standard of level I evidence.

Major Criticisms

• Not blinded
• Not real acupuncturists
• No mention of depth or angles of insertion
• Point prescription took no account of TCM differential diagnosis

At least some form of placebo acupuncture should have been incorporated into the control of the study, and would have been preferable in determining acupunctures effectiveness as a method of pain relief to having a TENS control group.

Validity of Conclusions

The conclusions drawn by the authors at the end of this study, align well with their findings. The conclusions also seem to agree with the majority of studies that preceded this one, in that pain scores didn't differ significantly, but the use of pharmacological analgesics or EDA was significantly reduced.

STUDY 2

MacKenzie, IZ, Xu, J, Cusick, C, Midwinter-Morten, H, Meacher, H, Mollison, J, Brock, H 2011, 'Acupuncture for Pain Relief During Induced Labour in Nulliparae: A Randomised Controlled Study', BJOG: An International Journal of Obstetrics and Gynaecology, Viewed 6 September 2012, <http://www.sciencedirect.com>.

Objective

To assess the role of acupuncture for anagesia during labour.

Design

The study was designed as a 'Double-blind study of manual, electro and sham acupuncture, and single-blind study comparing acupuncture with a control group for analgesia for labour induction' (MacKenzie et al. 2011: 440).

Setting

The maternity department of the John Radcliffe Hospital, Oxford, UK.

Funding

Funding for this research was not specified.

Inclusion / Exclusion Criteria

Nulliparae with singleton pregnancy and fetal cephalic presentation with intact membranes undergoing labour induction using vaginal prostaglandins and low amniotomy for prolonged gestation or mild hypotension in the John Radcliffe Hospital were eligible. Those with previous experience of acupuncture treatment were excluded.

Power Calculation

The group size in this study was calculated based on a previous study that observed a 50% reduction in the use of EDA. To achieve a 50% reduction from 70% of 'eligible' woman who had received an EDA in the same hospital in 2004, to 35% using acupuncture, it was calculated that 23 subjects were needed in each group. This would have 80% power to detect a 50% reduction in epidural rate. To accommodate for dropouts and violations, 26 subjects were recruited to each group.

Recruitment, Randomisation and Blinding

Subjects were recruited to the study through community midwives and obstetricians, and cunningly placed posters in antenatal clinics. After low enrolment in the first 6 months, eligible patients were located in the Induction of Labour Booking Register in the delivery suit, and then contacted and invited to participate in the study.

The subjects were randomised into four groups in an even 1:1:1:1 ratio. The four groups were electro-acupuncture, manual acupuncture, sham acupuncture, and no treatment groups. The sham group was further divided into sham-manual acupuncture and sham-electro acupuncture in a 1:1 ratio. Randomisation was computer generated, and allocations were concealed in envelopes. While the acupuncturist was aware of the treatment allocation, the other care staff and study authors were not. The authors have called this double-blind.

Practitioner

Acupuncture was provided by qualified acupuncturists registered either with the British Acupuncture Council or the Association of Traditional Chinese Medicine (UK).

Diagnosis of Individual Patterns / Prescription of Points / Treatment

All patients in the acupuncture and electro-acupuncture groups received the same point prescription and needling. There was no differentiation of TCM patterns, and no individualised treatment principle or point prescription.

Treatment began after induction had been started but before contractions began. Needles used were Seirin 0.20x30mm and 0.30x50mm. Needles were inserted to a depth of 15-20mm and de qi was obtained. Needles were retained for 30–60 minutes while the participants mobility was restricted. The following points were needled bilaterally, L.I.-4, Sp-6, BL60, BL67. Points were stimulated intermittently for 30 minutes following insertion. Treatment in the electro group used the same points, which were stimulated for 30 minutes.

Sham Control

Sham manual acupuncture used non-acupoints adjacent to treatment points. Needles were inserted only to a depth of 1-1.5mm, they were not stimulated, and no sensation of de qi was achieved. Sham-electro treatment involved the same location and insertion as the manual sham treatment, but the needles were connected to the electro stimulator, but no current was applied.

Dropouts and Violations

There were two violations during the study. One participant randomised to the control group received manual acupuncture. Another participant was randomised to the elecro-acupuncture group but withdrew from the study.

Overall Quality and Level of Evidence

The study was described as double-blind, and neither the participants, the attending midwives, nor any of the study authors were aware of the allocations of participants to groups. The acupuncturist performing the treatment was, necessarily, aware of the allocation. The implication is that this, despite every other precaution being taken, is not a full double-blind study. The Quality of the study and the level of evidence is still high, and rates 4 on the Jadad scale.

Outcome Measurements and Results

The primary outcome variable was the rate of intrapartum epidural anaesthesia requirement. Demographic details, labour management, duration and outcome, especially analgesia requirement, delivery method, including the indication for caesarean section, and neonatal outcome assessed by Apgar scores and cord blood-gas values were recorded for all subjects.

This study did not find that either acupuncture or electro-acupuncture reduced the need for epidural anaesthesia. While there was non-significant tendency toward lower analgesic requirement and caesarian section rate for the acupuncture group, the authors point out that the study was not sufficiently powered to identify these differences. No detrimental side effects were identified, and no follow-up questionnaire or survey was conducted.

Validity of Conclusions and Major Criticisms

Given the outcomes measured the authors conclusio that acupuncture does not reduce the need for epidural anaesthesia is valid. However, induced, and augmented labours are typically more painful than spontaneous labours, and this might change the outcome, specifically related to the use of EDA compared to studies of women undergoing spontaneous labour.

• The points used were not based on a diagnosis of the participant.
• Although they had enough participants as determined by their power calculation, the sample size was very small.
• Drawing the conclusion that acupuncture does not reduce the need for EDA, in a study group of patients, who had all had their labours induced does not seem reasonable. Especially, given the fact that induction and augmentation of labour, due to the intensity of the contractions they cause, lead to a higher chance that an EDA will be used.
• In this case, a frequency of EDA similar to that of naturally labouring woman, should be considered a successful outcome.

Conclusion

From the studies compiled and presented for this report, it seems clear that acupuncture as an adjunctive treatment to reduce pain and increase relaxation deserves more research. Although MacKenzie et al. concluded that acupuncture did not reduce the use of epidural anaesthesia, it was the only study measuring that particular outcome that had this result. This could be due to the fact that the study was conducted only on women who had their labour artificially induced. All studies conducted on women who went into spontaneous labour have so far had statistically significant reduction in the used of EDA's, and most have shown a subjective reduction in pain. It is my opinion that further research, utilising well designed double-blind placebo controlled RCT's is warranted. 

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