A new study has drawn together findings from hundreds of clinical trials to identify the most effective and safest pain relief option available to women during labour.
It finds the strongest evidence for drugs, though some non-drug methods may work and improve women’s satisfaction with their pain relief. Other popular options are not backed by research.
A new study has analysed the findings from 310 trials of labour pain relief options, evaluating the evidence for different therapies. The research is published this week in the Cochrane Database of Systematic Reviews.
Following analysis, the researchers split interventions into three categories:
WHAT WORKS
- Pain-relieving drugs given by epidural, combined spinal epidural (CSE) or inhalation
WHAT MAY WORK
- Immersion in water, relaxation, acupuncture, massage and local anaesthetic nerve blocks or non-opioid drugs
INSUFFICIENT EVIDENCE
- Hypnosis, biofeedback, sterile water injection, aromatherapy, transcutaneous electrical nerve stimulation (TENS) and injected or intravenous opioids
However, more adverse effects were associated with the interventions for which there was the best evidence, including nausea and vomiting caused by inhaled painkillers and hypotension due to epidural.
The second group of pain relief approaches, although less well-supported by clinical evidence, were better tolerated, with women reporting improved satisfaction with pain relief for all except massage.
Dr Michelle Wise Senior Lecturer, Department of Obstetrics and Gynaecology, University of Auckland Obstetrician and Gynaecologist, Auckland District Health Board, commented (an excerpt):
“When I was a university student, my professor at the time Dr Ron Melzack explained to our class that labour pain is the most severe pain that a woman experiences in her lifetime,scoring 10 out of 10 on the Melzack Pain Scale that is still used today in all areas of medicine. The Cochrane review is a comprehensive and thorough review of the multitude of options for pain relief in labour, and reflects the importance of this issue to women. Over 63 000 women gave birth in New Zealand in 2009, and the majority of them likely used at least one of the therapies mentioned in this review. This research methodology of this review is of the highest quality, and provides an excellent background to the conversation that I have with pregnant women in my care every day.
“The findings of the review are not new findings, and in fact, it is reassuring to see that they confirm what we already know. For example, in their review of 65 studies of over 12 000 women, the authors conclude that Epidural effectively relieves labour pain, has some minor and expected side effects such as low blood pressure, and although there is a slight increase in assisted vaginal births, epidurals do not make women more likely to have a caesarean section. Thus this review will not change my practice, especially as an obstetrician where I am involved in more complicated births where women are more likely to require an epidural.
“What this review highlights, though, is that for all the non-drug interventions and for some of the drug therapies, there is very little or poor quality research studies to help us decide if they are effective in relieving labour pain, and how safe they are, both for the mothers and for their babies.
“For example, women who receive injections of opioids such as Pethidine are more drowsy and nauseated, which may prolong labour, and may impact their ability to make clear decisions about their care. Opioids readily cross the placenta and it is estimated that newborns can take 3-6 days to eliminate the breakdown product of pethidine from their system, which may affect breastfeeding. Only 3 studies compared opioid use to placebo. One study of 50 women found that women who used opioids had lower pain scores, but all 3 studies showed no difference in satisfaction with pain relief or with childbirth experience. None looked at breastfeeding as an outcome. This review suggests that there is not enough information to help us decide if opioids are more effective than any other non-drug option for pain relief, and even less information to reassure us that they are safe.
“The significance of this study in the New Zealand setting is that all the reviewed options for pain relief (except Epidural) are within the scope of midwifery care. Thus as an obstetrician I cannot directly comment on its implications for planning pain management in labour. That being said, there is very high regard in maternity care for patient autonomy and informed consent for any intervention during pregnancy, labour and birth, and we need to ensure that women who choose to use certain pain relief options in labour (such as opioids) are told that until better studies are available, these options may or may not relieve the pain and may or may not have negative effects on her well-being in labour and on her baby.
“I agree with the authors that high quality trials are needed, and I think we as a research community including doctors and midwives in future will be able to give far better advice to pregnant women than we do at the moment.”
Karen Guilliland, CEO, New Zealand College of Midwives, commented:
“I agree that there is a need for further research so that women can be confident in the choices they make around managing pain in labour. However pain is so subjective and variably experienced it is a difficult topic to research with confidence. Narcotics and analgesics can also interfere with memory and recall which also further confounds the ability to study the true situation.
“Some drugs also interfere with the normal processes of birth and the women’s experience is altered as a result of the treatment rather than the birth process. For example the need for forceps birth is increased with some drugs and this is in itself a difficult and painful experience. Most drugs have side effects which make them unacceptable to some women.”
“Fear of birth is also a major contributor to pain levels. Managing fear through trust and negotiation is therefore an essential element of labour care regardless of drug choices. The other issue is that, research or not, many of the non-opiod measures to relieve pain are learned during childhood and are therefore culturally imposed. Massage, distraction, heat, and vocal relief will be used by most women at some point of their labour and birth. Warm water, positioning, acupressure will continue to be appropriate for most women.
“Funding for non-drug approaches to managing pain in labour is also notoriously difficult to attract so there has been limited research conducted on the topic.
“As the authors of the review note: “despite concerns for 30 years or more about the effects of maternal opioid administration during labour on subsequent neonatal behaviour and its influence on breastfeeding, only two out of 57 trials of opioids reported breastfeeding as an outcome”. Breastfeeding is a major public health issue and the lack of research around the effects of analgesic drugs on the initiation and duration of breastfeeding is urgent as is the wider issue of the choices that can be made to relieve pain in labour.
“From a midwifery perspective, as health professionals we work alongside women, supporting them during their pregnancy, labour and following the birth of their baby. Every woman has a slightly different perception and expectation about the level of pain they are comfortable with. The different forms of pain relief have varying effectiveness and all of them will impact on how a labour progresses. It is important for women to fully understand the implications of these forms of pain relief before they consider using them.
“Pharmacological pain relief is often the first step in a cascade of interventions that can occur because it alters your body’s normal hormonal responses to the physiological processes of labour and birth. While in labour, the various stages are activated physiologically by the pain and how the body manages that pain – whether it is the release of endorphins or other natural chemicals, and this enables a woman’s body to do what it is made to do without those “triggers” being affected by drugs. Some of these drugs for example merely mirror the same effect of the bodies own pain management responses if allowed to develop. We have all heard of the marathon runner who feels no pain until the end.
“That is not to say pharmacological pain relief shouldn’t be considered or used however women must be provided with information on all the options so that they are able to make a fully informed decision when it comes to pain relief. More research is essential to that.
“We do know continuity of care research shows this close relationship reduces pain levels and increases women’s satisfaction with the experience. Continuity of care by midwives includes important considerations such as cultural beliefs and traditions, whanau support, place of birth; these all play a part in the choices a woman may make when it comes to pain relief. A woman will feel more confident about what her body can do and about the choices she has made when she is comfortable with the place she is having her baby and the people supporting her. That confidence, and this is supported by midwifery research, plays a major part in effectively managing labour and encourages positive outcomes for both mum and baby.
“The most requested publications the NZ College of Midwives produces is a booklet called “Pain in Labour” which was updated in mid 2010. It contains a great deal of information on all the options when it comes to pain relief and the feedback we receive about the booklet, from women and midwives, is excellent. Full research sources are provided in ‘Pain in Labour’ .”
A copy of ‘Pain in Labour’ is available from the SMC on request.
Our colleagues at the UK SMC collected the following expert commentary:
Peter Brocklehurst, Professor of Women’s Health and Director of the Institute for Women’s Health at University College London said:
“This important ‘review of reviews’ clearly shows that many methods of pain relief in labour, particularly non-drug methods such as massage and immersion in water, are not well researched. For example, we have good evidence about how effective epidurals are, but we also know they have problems, including an increased risk of forceps and ventouse births. On the other hand, when it comes to many other, non-drug, interventions such as massage and TENS, the evidence base is much poorer. This does not mean that these methods don’t work – just that we don’t know whether they do or do not work because the research needed to know this has not been done.
“Altogether this means that women may be using methods which are not effective, or being denied methods which are effective and which may improve their labour without them having to use epidurals. We urgently need to do this research so that women know what works and what doesn’t.