Cochrane Database Syst Rev. 2012 Mar 14;3:CD009234.
Pain management for women in labor: an overview of systematic reviews.
Jones L, Othman M, Dowswell T, Alfirevic Z, Gates S, Newburn M, Jordan S, Lavender T, Neilson JP.
Cochrane Pregnancy and Childbirth Group, Department of Women’s and Children’s Health, The University of Liverpool, Liverpool, UK.
The pain that women experience during labor is affected by multiple physiological and psychosocial factors and its intensity can vary greatly. Most women in labor require pain relief. Pain management strategies include non-pharmacological interventions (that aim to help women cope with pain in labor) and pharmacological interventions (that aim to relieve the pain of labor).
To summarise the evidence from Cochrane systematic reviews on the efficacy and safety of non-pharmacological and pharmacological interventions to manage pain in labor. We considered findings from non-Cochrane systematic reviews if there was no relevant Cochrane review.
We searched the Cochrane Database of Systematic Reviews (The Cochrane Library 2011, Issue 5), The Cochrane Database of Abstracts of Reviews of Effects (The Cochrane Library 2011, Issue 2 of 4), MEDLINE (1966 to 31 May 2011) and EMBASE (1974 to 31 May 2011) to identify all relevant systematic reviews of randomized controlled trials of pain management in labor.
Each of the contributing Cochrane reviews (nine new, six updated) followed a generic protocol with 13 common primary efficacy and safety outcomes. Each Cochrane review included comparisons with placebo, standard care or with a different intervention according to a predefined hierarchy of interventions. Two review authors extracted data and assessed methodological quality, and data were checked by a third author. This overview is a narrative summary of the results obtained from individual reviews.
We identified 15 Cochrane reviews (255 included trials) and three non-Cochrane reviews (55 included trials) for inclusion within this overview. For all interventions, with available data, results are presented as comparisons of:
1. Intervention versus placebo or standard care;
2. Different forms of the same intervention (e.g. one opioid versus another opioid);
3. One type of intervention versus a different type of intervention (e.g. TENS versus opioid).
Not all reviews included results for all comparisons. Most reviews compared the intervention with placebo or standard care, but with the exception of opioids and epidural analgesia, there were few direct comparisons between different forms of the same intervention and even fewer comparisons between different interventions.
Based on these three comparisons, we have categorized interventions into: " What works", "What may work", and "Insufficient evidence to make a judgment".
Evidence suggests that epidural, combined spinal-epidural (CSE) and inhaled analgesia effectively manage pain in labor, but may give rise to adverse effects. Epidural, and inhaled analgesia effectively relieve pain when compared with placebo or a different type of intervention (epidural versus opioids).
Combined-spinal epidurals relieve pain more quickly than traditional or low dose epidurals. Women receiving inhaled analgesia were more likely to experience vomiting, nausea, and dizziness.
When compared with placebo or opioids, women receiving epidural analgesia had more instrumental vaginal births and cesarean sections for fetal distress, although there was no difference in the rates of cesarean section overall. Women receiving epidural analgesia were more likely to experience hypotension, motor blockade, fever or urinary retention. Less urinary retention was observed in women receiving CSE than in women receiving traditional epidurals. More women receiving CSE than low-dose epidural experienced pruritus.
WHAT MAY WORK
There is some evidence to suggest that immersion in water, relaxation, acupuncture, massage, and local anesthetic nerve blocks or non-opioid drugs may improve the management of labor pain, with few adverse effects. Evidence was mainly limited to single trials. These interventions relieved pain and improved satisfaction with pain relief (immersion, relaxation, acupuncture, local anesthetic nerve blocks, non-opioids) and childbirth experience (immersion, relaxation, non-opioids) when compared with placebo or standard care. Relaxation was associated with fewer assisted vaginal births and acupuncture was associated with fewer assisted vaginal births and cesarean sections.
There is insufficient evidence to make judgments on whether or not hypnosis, biofeedback, sterile water injection, aromatherapy, TENS, or parenteral opioids are more effective than placebo or other interventions for pain management in labor. In comparison with other opioids more women receiving pethidine experienced adverse effects including drowsiness and nausea.
Most methods of non-pharmacological pain management are non-invasive and appear to be safe for mother and baby, however, their efficacy is unclear, due to limited high-quality evidence. In many reviews, only one or two trials provided outcome data for analysis and the overall methodological quality of the trials was low.
High-quality trials are needed. There is more evidence to support the efficacy of pharmacological methods, but these have more adverse effects.
Thus, epidural analgesia provides effective pain relief but at the cost of increased instrumental vaginal birth. It remains important to tailor methods used to each woman's wishes, needs, and circumstances, such as anticipated duration of labor, the infant's condition, and any augmentation or induction of labor.
A major challenge in compiling this overview, and the individual systematic reviews on which it is based, has been the variation in use of different process and outcome measures in different trials, particularly the assessment of pain and its relief, and effects on the neonate after birth. This made it difficult to pool results from otherwise similar studies, and to derive conclusions from the totality of evidence.
Other important outcomes have simply not been assessed in trials; thus, despite concerns for 30 years or more about the effects of maternal opioid administration during labor on subsequent neonatal behavior and its influence on breastfeeding, only two out of 57 trials of opioids reported breastfeeding as an outcome.
We therefore strongly recommend that the outcome measures agreed through wide consultation for this project, are used in all future trials of methods of pain management.