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Sir,

Wassen et al.1 have conducted a meta-analysis of randomised controlled trials (RCTs) of women receiving epidural analgesia early versus later in labour. They concluded that the early use of epidural analgesia does not result in an increase in either instrumental delivery or caesarean section. The meta-analysis is primarily about caesarean section, so the title is misleading. Six studies met their criteria for inclusion—all of which have problems.

Luxman (1998)2 conducted an underpowered RCT in an environment that had a very low rate of caesarean section in both the experimental and the control arms (6 versus 10%). Wong et al.3 received much play in the in the press—claiming that early epidurals do not increase the caesarean section rate. Their RCT of 705 nulliparous women was not on epidural analgesia per se, but on combined spinal and epidural analgesia, with a substantial delay between the spinal and the epidural, which is not how combined spinal and epidural analgesia is usually employed. At first request for pain relief, women got the spinal or a narcotic. At the second request, women received an epidural or a narcotic. By the second request, women in the experimental (spinal–epidural) and control (narcotic) arms were in advanced labour. Hence, the study was not about early epidurals at all. Ohel et al.4 studied 449 nulliparous women, and convincingly showed no difference between early and late epidurals, but the study took place in a an environment with a low rate of caesarean section (13 versus 11%). Wang et al.5 reported on a huge 5-year Chinese study, perhaps the largest study of its kind in obstetrics, of 12 993 nulliparous women, showing that even use in the latent phase, compared with later, led to no difference. It was really very early compared with later, rather than late. There was a very high rate of intervention in both arms, but the rate of caesarean section was modest (23–24%), although not at our current common rates of up to or exceeding 30%. Wong et al.6 reported on a second study by the same group, in which nulliparous women were again exposed to combined spinal and epidural analgesia, and not epidural, but it was of induced women only. Hence its external validity to women in spontaneous labour is questionable.

This meta-analysis illustrates the old issue of what constitutes the type of study that should be included in a meta-analysis. In my opinion, the only study that speaks to the issue at hand is that of Ohel et al.4 One can conclude that in this setting, an early epidural will not lead to an increase in the rate of caesarean section. However, most of the environments in North America and most Western countries do not have a caesarean section rate of 11–13%. Thus, the Ohel study illustrates that if we could approach such a low caesarean section rate, epidurals are not likely to be a problem. In fact we could all learn from Ohel and company about how they achieve such a low rate of caesarean section.

References

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  2. References
  • 1
    Wassen MMLH, Zuijlen J, Roumen FJME, Smits LJM, Marcus MA, Nijhuis JG. Early versus late epidural analgesia and the risk of instrumental delivery in nulliparous women: a systematic review. BJOG 2011;118:65561.
  • 2
    Luxman D, Wolman I, Groutz A, Cohen JR, Lottan M, Pauzner D, et al. The effect of early epidural block administration on the progression and outcome of labor. Int J Obstet Anesth 1998;7:1614.
  • 3
    Wong CA, Scavone BM, Peaceman AM, McCarthy RJ, Sullivan JT, Diaz NT, et al. The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med 2005;352:65565.
  • 4
    Ohel G, Gonen R, Vaida S, Barak S, Gaitini L, Ohel G, et al. Early versus late initiation of epidural analgesia in labor: does it increase the risk of cesarean section? A randomized trial Am J Obstet Gynecol 2006;194:6005.
  • 5
    Wang F, Shen X, Guo X, Peng Y, Gu X, Labor Analgesia Examining Group, et al. Epidural analgesia in the latent phase of labor and the risk of cesarean delivery: a five-year randomized controlled trial. Anesthesiology 2009;111:87180.
  • 6
    Wong CA, McCarthy RJ, Sullivan JT, Scavone BM, Gerber SE, Yaghmour EA, et al. Early compared with late neuraxial analgesia in nulliparous labor induction: a randomized controlled trial. Obstet Gynecol 2009;113:106674.