Drug-based approaches are more effective in relieving labor pain than non-drug approaches, evidence reveals. These are the findings of an all-encompassing publishing in The Cochrane Library, which draws together results from a number of previous reviews on the subject.
Many different approaches are used to relieve pain in labor, but not all are supported by strong evidence. The researchers brought together the results of 15 previous Cochrane reviews and three non-Cochrane reviews, including data from 310 trials in total. To try to distinguish between well-supported and less well-supported pain relief approaches, they decided to split interventions into three categories.
Painkilling drugs given by epidural, combined spinal epidural (CSE) and inhalation fell under the first category, "what works". There was less evidence for immersion in water, relaxation, acupuncture, massage and local anaesthetic nerve blocks or non-opioid drugs. The authors classed these interventions as "may work". 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. The least supported or "insufficient evidence" group of pain relief interventions included hypnosis, biofeedback, sterile water injection, aromatherapy, transcutaneous electrical nerve stimulation (TENS) and injected or intravenous opioids.
The overview study calls for more research on the non-drug interventions that researchers grouped into the second and third categories. Although generally safe, for most of these interventions, evidence was based on just one or two trials. Fewer than 1,000 women have taken part in trials for each of hypnosis, biofeedback, sterile water injection, aromatherapy and massage. TENS is popular and widely recommended by midwives but not by the National Institute for Health and Clinical Excellence. "The discordance of views between women, clinicians and guidelines reflects a poor evidence base and the uncertainty should be resolved by a definitive clinical trial," said Neilson.