Wednesday March 14 2012
Evidence suggests many pain relief options may have benefits
A major new study of pain relief during labour was widely reported in the papers today, with the Daily Express claiming that drugs work better than drug-free alternatives such as massage, and the Daily Mail reporting that painkillers are more effective than hypnosis or electronic pain-relief machines.
In fact, these headlines were misleading and oversimplified the results of this large review, which looked at all high-quality research on pain management during labour. It found there is generally better evidence available for the effectiveness of drugs to relieve labour pains (including epidurals), and less robust evidence for non–drug approaches such as hypnosis.
However, saying there is less evidence on certain methods is not the same as saying these methods ‘do not work as well’. As the authors make clear, it means that, to date, there have been few good quality studies confirming how effective they may or may not be.
The review also points out that most drug-based approaches can have side effects. Epidurals, for example, increase the risk of further interventions such as forceps. It is also noteworthy that one of the interventions for which there is little evidence is the use of intramuscular painkillers such as pethidine, which is commonly used in many obstetric units.
This review provides good insight into what options women might prefer during birth, which can be discussed and noted when making a birth plan.
Where did the review come from?
The review was undertaken by researchers from the Cochrane Collaboration, a respected international research group that carries out independent reviews of the evidence on healthcare treatments. The rigorous methods these reviews employ mean that they are among the best evidence sources for evaluating medical procedures.
In this particular review the researchers drew together the results of a number of previous systematic reviews on the subject of pain relief during labour. They then used well-established methods to identify relevant research and to assess its quality. In total, they brought together 15 previous Cochrane reviews on the subject and three non-Cochrane reviews, and used them to assess a range of pain relief options.
Why was this review needed?
The type and intensity of pain that women experience during labour can vary greatly. It can be affected by many physiological and psychosocial factors, including fear and anxiety, prior experience and the degree of emotional support they receive. Most women require some form of pain relief.
While there are several drug and non-drug options available, the reviewers point out there has not yet been a single evidence source pulling together all the evidence from good trials on pain management in labour. The new overview aims to provide a summary of all the good quality evidence, both for medical professionals and pregnant women.
What pain relief methods did it look at?
The review covered a number of pain relief methods including:
- epidurals: is an injection of anaesthetic drugs in between the spinal bones but outside the spinal cord, and can be delivered either through single injections or fed as needed through a fine tube left in the lower back
- Combined spinal epidurals (CSE): as per a regular epidural a CSE is a low dose injection of fast-acting pain relief (a mini-spinal), but an epidural tube is also placed so that further drugs can be given as the effects of the mini-spinal wear off. The aim of CSEs is to provide faster pain relief than epidurals alone.
- inhaled analgesia: known as Entonox or ‘gas and air’
- injected or intramuscular opioid painkillers (such as pethidine)
- non-opioid painkillers: such as paracetamol, ibuprofen and so on.
- local anaesthetic nerve blocks
- sterile water injections: injected into the skin over the base of the spine
- immersion in water: when a woman uses a special pool during labour
- relaxation methods: such as breathing and yoga
- biofeedback: where the woman receives signals as to her pulse, heart rate etc.)
- aromatherapy: the use of essential oils
- Transcutaneous electrical nerve stimulation (TENS): a mild electric current is passed through the skin to reduce nerve pain signals
What did the reviewers find?
The reviewers divided the different pain relief methods into different categories, according to how much good quality evidence had been carried out on each of them. The three categories were
- what works
- what may work
- insufficient evidence to make a judgement
The reviewers found that there is good evidence for both forms of epidurals, and that CSEs gave faster pain relief than standard epidurals alone. There was more limited evidence for gas-based pain relief (inhaled analgesia) methods during labour, although the research still supported their use.
Both epidurals and inhaled analgesia can have adverse effects. The review found that inhaled analgesia is associated with nausea and vomiting, while epidurals increased the number of vaginal births needing a forceps or ‘ventouse intervention’, a technique using a suction cup to help deliver the baby. Epidurals also increased the risk of low blood pressure for the mother, as well as other side effects such as being unable to pass urine and having difficulty moving one’s legs.
What may work?
The review found there is some evidence to suggest that immersion in water, relaxation, acupuncture, massage, local anaesthetic nerve blocks and non-opioid drugs (for example, paracetamol and NSAIDs) may help to manage labour pains, with few adverse effects.
Women reported satisfaction with the pain relief they gained from all these interventions, apart from massage.
Relaxation and acupuncture reduced the need for forceps and ventouse interventions, and acupuncture reduced the number of caesarean sections. However, the researchers point out the evidence for each of these methods was mainly limited to a few individual trials (rather than systematic reviews).
Where is more evidence needed?
The researchers found ‘insufficient evidence to make a judgement’ on the effectiveness of:
- sterile water injections
- injected or intramuscular opioids
What happens now?
The reviewers say that the trials they looked at showed ‘considerable variation’ in how outcomes such as pain intensity were measured and that some important outcomes were never included. For example, no studies examined a woman’s sense of control during labour, the effect of pain relief on the ability to breastfeed and on mother-baby bonding, despite surveys showing that these factors are important to women.
Designing future trials that include these factors is essential, the researchers argue. In addition, further good quality research on the effectiveness of non-drug interventions during labour is needed.
The authors say that during pregnancy women should be told about the benefits and the potential adverse effects of all available pain relief methods, both for them and their babies. They should feel free to choose whatever pain management they think would help them most.
What kind of pain relief should I choose?
The choice of pain relief during labour will be an individual one, and clearly there are benefits and drawbacks to each that must be considered. However, this review provided a good overview of the various types of pain relief available during labour, and how much evidence there is supporting their use.
Women do not have to make this choice alone, as they can get medical advice from their doctor or midwife on what may suit them best. Women can do this when creating a birth plan setting out other options such as where they will give birth.
Importantly, women who choose non-drug pain management should feel free to move on to a drug-based intervention if needed, and might benefit from planning a back-up pain relief option if their initial choice is not effective during the birth.