November 02, 2017
Research Review: Epidurals Don’t Slow Labor? The Devil Is in the Details
By: Henci Goer, BA | 0 Comments
By Henci Goer
Making the rounds on the internet is a report of a new study that supposedly shows that epidurals don't slow labor or increase instrumental vaginal or cesarean delivery. . . . Um, not exactly. The study actually showed that discontinuing an epidural in second stage didn't increase second stage duration or decrease spontaneous vaginal birth, which isn't quite the same thing. Let's take a closer look.
Conducted in China, investigators randomly allocated 400 healthy, nulliparous women, 200 per group, to have their epidural solution replaced with saline or to continue the anesthetic at full cervical dilation. Who got which solution was concealed from everyone involved.
Outcomes were similar on all measures for saline vs. continuing epidural:
- Mean 2nd-stage duration: 51 plus or minus 25 min vs. 52 plus or minus 27 min
- Occiput posterior or transverse at delivery: 3% vs. 4%
- Cesarean delivery: 0% vs. 1%
- Forceps delivery: 1% vs. 2.5%
- Mean pain scores and interquartile range on a 10 cm unmarked visual scale
- at initiation of epidural: 8 (7-9)
- at initiation of study solution: 1.2 (0.6-2.3) vs. 1.5 (0.7-2.7)
- 30 min: 1.4 (0.6-2.4) vs. 1.3 (0.8-2.0)
- 60 min: 1.5 (0.9-1.5) vs. 1.1 (0.5-2.0)
- 90 min: 3.1 (1.6-3.3) vs. 2.4 (1.2-3.1)
- Treatment for breakthrough pain: 2% vs.3%
Maternal satisfaction differed modestly. All women receiving the epidural solution scored their satisfaction as '10' on an 11-point scale whereas women receiving saline scored satisfaction at a median of 9 with an interquartile range of 8-10.
Theoretically, discontinuing an epidural could make pushing more effective, which could increase spontaneous birth rates, but discontinuation had no effect. While that doesn't matter in this population, where cesarean and instrumental vaginal delivery rates could hardly be lower, it could matter in other populations differently managed. The pain and satisfaction data give us a clue as to why discontinuation wouldn't work regardless of circumstances: the anesthetic doesn't wear off fast enough to make a difference.
But the zero effect of discontinuing an epidural is hardly new news. A Cochrane systematic review concluded as much back in 2004. Reviewers included five trials totaling 462 nulliparous women, four of which were published between 1987 and 1990 and the fifth of which was published in 1996.
As you might expect, those trials weren't comparable to this one. This trial was of patient-controlled analgesia with 0.8% ropivacaine, which study authors note was equivalent to 0.05% bupivacaine, whereas four of the trials in the systematic review used continuous infusions of 0.75% lidocaine, 0.125% bupivacaine, 0.0625% bupivacaine + fentanyl, and 2.5 mg/ml bupivacaine; and the fifth trial administered periodic top-ups of 0.25% bupivacaine. This trial began at full dilation whereas the trials in the review began at 8 cm dilation or later.
Results were somewhat different too. While absolute percentages were higher in the review, pooled cesarean rates were identical (6%) and fetal malposition rates were similar (11% vs. 8%) between groups. However, unlike the new trial, the review showed a possible reduction in instrumental delivery rates (22% vs. 28%) with epidural discontinuation - although results might have been due to chance - and substantially more women reported inadequate pain relief (22% vs. 6%). Still, the review failed to support a policy of withholding epidural analgesia in the second stage in hopes of increasing spontaneous vaginal birth, which raises the question of why they conducted the new trial in the first place, especially in the modern era of low-dose epidurals.
Contrary to how this new trial is being positioned, it in no way contradicts that epidurals increase the likelihood of instrumental vaginal delivery and arguably, cesarean delivery. All it tells us is that women should not be deprived of an epidural in second stage because the only thing discontinuation accomplishes is possibly increasing their discomfort. But, then, we already knew that.
Shen, X., Li, Y., Xu, S., Wang, N., Fan, S., Qin, X., ... & Hess, P. E. (2017). Epidural Analgesia During the Second Stage of Labor: A Randomized Controlled Trial. Obstetrics & Gynecology, 130(5), 1097-1103.
Torvaldsen, S., Roberts, C. L., Bell, J. C., & Raynes - Greenow, C. H. (2004). Discontinuation of epidural analgesia late in labour for reducing the adverse delivery outcomes associated with epidural analgesia. The Cochrane Library.
About Henci Goer
Henci Goer, award-winning medical writer and internationally known speaker, is an acknowledged expert on evidence-based maternity care. Her first book, Obstetric Myths Versus Research Realities, was a valued resource for childbirth professionals. Its successor, Optimal Care in Childbirth: The Case for a Physiologic Approach, won the American College of Nurse-Midwives 'Best Book of the Year' award. Goer has also written The Thinking Woman's Guide to a Better Birth, which gives pregnant women access to the research evidence, as well as consumer education pamphlets and articles for trade, consumer, and academic periodicals; and she posts regularly on Lamaze International's Science & Sensibility. Goer is founder and director of Childbirth U, a website offering narrated slide lectures to help pregnant women make informed decisions and obtain optimal care for themselves and their babies.
TagsEpidural Pushing Second Stage Professional Resources Labor/Birth Epidurals Henci Goer Labor And Birth Research Review