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Elective Induction at 40 Weeks? “Decision-Based Evidence Making” Strikes Again

July 14th, 2015 by avatar

Today on Science & Sensibility, contributor Henci Goer takes a look at a systematic review released in spring that examined the impact of elective inductions on the cesarean rate.  Sound analysis or a house of cards?  Looking closer at the studies reviewed provides insight into how the conclusions reached by the investigators might need to be examined more closely.  Henci does that in this review.  Have you read this new systematic review?  Did you come to the same conclusions?  I invite you to share your thoughts in our comments section below. – Sharon Muza, Community Manager, Science & Sensibility.

flickr photo by catharticflux http://flickr.com/photos/catharticflux/2710057340  CC licensed.

flickr photo by catharticflux http://flickr.com/photos/catharticflux/2710057340 CC licensed.

Yet another systematic review has surfaced “Induction of labor at full term in uncomplicated singleton gestations: a systematic review and metaanalysis of randomized controlled trials”  in which reviewers claim that electively inducing healthy women, this time at 40, not 41 weeks, offers benefits and doesn’t increase the cesarean surgery rate (Saccone 2015).

Let’s take a closer look.

Reviewers included five trials: three of them conducted in the 1970s (Cole 1975; Martin 1978; Tylleskar 1979), the fourth published in 2005 (Nielsen 2005), and the fifth in 2014 (Miller 2014). Already we have a problem. Induction management in the 1970s is sufficiently different from management today that results are unlikely to apply to contemporary care, but let’s get down to specifics. Two of the 1970s trials were deemed inadequate for inclusion in the Cochrane review of elective induction (Gulmezoglu 2012), and Miller 2014 is published only as an abstract. Quality systematic reviews exclude abstracts because they don’t provide enough information to evaluate the study. For these reasons, these three trials should be taken off the table..

That leaves us with the other two. Nielsen 2005 states in the title “Comparison of elective induction of labor with favorable Bishop scores versus expectant management: a randomized clinical trial” that it is confined to women with favorable Bishop scores. Anyone familiar with elective induction research should know that inducing when the cervix is ready to go won’t increase the cesarean rate compared with spontaneous onset, but inducing with an unripe cervix is a different story even when using cervical ripening agents (Dunne 2009; Jonsson 2013; Le Ray 2007; Macer 1992; Prysak 1998; Thorsell 2011; Vahratian 2005). As you move the induction date earlier and earlier, more and more women will have an unfavorable cervix, so including a trial limited to women with a ripe one will tilt the playing field in favor of induction. Furthermore, half the participants were multiparous women (113/226). Women with prior vaginal births will go on having vaginal births pretty much no matter what you do to them, which raises another point: inducing earlier means a higher percentage of the inductees will be first-time mothers because first time mothers tend to run longer pregnancies (Mittendorf 1990). Nulliparous women are much more vulnerable to anything that pushes them in the direction of a cesarean. That’s not all: The authors tell us that their hospital has a 7% cesarean rate for dystocia in women at term. If a hospital has a cesarean rate much higher than that—and many do—then results can’t be generalized to it, although, frankly, if the doctors are performing cesareans left and right, induction or spontaneous onset may not make much difference. In short, Nielsen (2005) doesn’t make a compelling argument for 40-week elective induction.

flickr photo by Selbe <3 http://flickr.com/photos/stacylynn/11944718954 shared under a Creative Commons (BY-NC-ND) license

flickr photo by Selbe < http://flickr.com/photos/stacylynn/11944718954 shared under a Creative Commons (BY-NC-ND) license

This brings us to the last trial, Cole (1975). Investigators allocated healthy women either to induction at 40 weeks (111 women) or 41 weeks (117 women). As with Nielsen, half the women had prior vaginal births. Despite being healthy, 22 women were induced for “obstetric complications” (undefined) in the 41-week induction group before reaching 41 weeks. If their doctors induced labor because they had concerns, then this would likely put the women at heightened risk for cesarean. Another 32 women were induced for exceeding 41 weeks. This means that overall, nearly half (46%) of the comparison group didn’t begin labor spontaneously, which would mask any association between induction and cesarean. Leaving the induction vs. spontaneous onset issue aside, the U.S. cesarean rate in the early 1970s was around 5%, which means it was a rare woman who would have one regardless of circumstances. Again, not exactly a strong case for inducing at 40 weeks.

What about the benefits? The best reviewers can come up with are a clinically meaningless reduction in mean blood loss (-58 ml); a lower rate of meconium-stained amniotic fluid (4% vs. 14%), not, mind you, a reduction in meconium aspiration, and therefore clinically meaningless as well; and an equally meaningless reduction in mean birth weight of -136 g (5 oz). If they had found something more impressive, surely they would have reported it.

Really? This merited a pre-publication media blast? Because it amounts to a textbook example of “garbage in, garbage out.” I can see only three possibilities to explain it: either 1) the authors and peer reviewers at the American Journal of Obstetrics and Gynecology (AJOG) don’t know as much as they should about what constitutes a quality systematic review, 2) they are so steeped in medical model thinking—“How early can we get the baby out of that treacherous maternal environment?”—that their judgment is compromised, or 3) we have a “pay no attention to what’s behind the curtain” effort to promote elective induction. I don’t know which is the more troubling, but if it’s the last one, the sad thing is that because it’s got the magic words “systematic review,” “meta-analysis,” and “randomized controlled trials” in the title, it’s likely to succeed.

References

Cole, R. A., Howie, P. W., & Macnaughton, M. C. (1975). Elective induction of labour. A randomised prospective trial. Lancet, 1(7910), 767-770.

Dunne, C., Da Silva, O., Schmidt, G., & Natale, R. (2009). Outcomes of elective labour induction and elective caesarean section in low-risk pregnancies between 37 and 41 weeks’ gestation. J Obstet Gynaecol Can, 31(12), 1124-1130.

Gulmezoglu, A. M., Crowther, C. A., Middleton, P., & Heatley, E. (2012). Induction of labour for improving birth outcomes for women at or beyond term. Cochrane Database Syst Rev, 6, CD004945.

Jonsson, M., Cnattingius, S., & Wikstrom, A. K. (2013). Elective induction of labor and the risk of cesarean section in low-risk parous women: a cohort study. Acta Obstet Gynecol Scand, 92(2), 198-203. doi: 10.1111/aogs.12043

Le Ray, C., Carayol, M., Breart, G., & Goffinet, F. (2007). Elective induction of labor: failure to follow guidelines and risk of cesarean delivery. Acta Obstet Gynecol Scand, 86(6), 657-665.

Macer, J. A., Macer, C. L., & Chan, L. S. (1992). Elective induction versus spontaneous labor: a retrospective study of complications and outcome. Am J Obstet Gynecol, 166(6 Pt 1), 1690-1696; discussion 1696-1697.

Martin, D. H., Thompson, W., Pinkerton, J. H., & Watson, J. D. (1978). A randomized controlled trial of selective planned delivery. Br J Obstet Gynaecol, 85(2), 109-113.

Miller, N., Cypher, R., Pates, J., & Nielsen, P. E. (2014). Elective induction of nulliparous labor at 39 weeks of gestation: a randomized clinical trial. Obstet Gynecol,132(Suppl 1):72S.

Mittendorf, R., Williams, M. A., Berkey, C. S., & Cotter, P. F. (1990). The length of uncomplicated human gestation. Obstet Gynecol, 75(6), 929-932.

Nielsen, P. E., Howard, B. C., Hill, C. C., Larson, P. L., Holland, R. H., & Smith, P. N. (2005). Comparison of elective induction of labor with favorable Bishop scores versus expectant management: a randomized clinical trial. J Matern Fetal Neontal Med, 18:59-64.

Prysak, M., & Castronova, F. C. (1998). Elective induction versus spontaneous labor: a case-control analysis of safety and efficacy. Obstet Gynecol, 92(1), 47-52.

Saccone, G., & Berghella, V. (2015). Induction of labor at full term in uncomplicated singleton gestations: a systematic review and metaanalysis of randomized controlled trials. American journal of obstetrics and gynecology.

Thorsell, M., Lyrenas, S., Andolf, E., & Kaijser, M. (2011). Induction of labor and the risk for emergency cesarean section in nulliparous and multiparous women. Acta Obstet Gynecol Scand, 90(10), 1094-1099. doi: 10.1111/j.1600-0412.2011.01213.x

Tylleskar, J., Finnstrom, O., Leijon, I, et al. (1979). Spontaneous labor and elective induction – a prospective randomized study. Effects on mother and fetus. Acta Obstet Gynaecol Scand, 58:513-518.

Vahratian, A., Zhang, J., Troendle, J. F., Sciscione, A. C., & Hoffman, M. K. (2005). Labor progression and risk of cesarean delivery in electively induced nulliparas. Obstet Gynecol, 105(4), 698-704.out

About Henci Goer

Henci Goer

Henci Goer, award-winning medical writer and internationally known speaker, is the author of The Thinking Woman’s Guide to a Better Birth and Optimal Care in Childbirth: The Case for a Physiologic Approach She is the winner of the American College of Nurse-Midwives “Best Book of the Year” award. An independent scholar, she is an acknowledged expert on evidence-based maternity care.

 

ACOG, Cesarean Birth, Childbirth Education, Do No Harm, Evidence Based Medicine, Guest Posts, Medical Interventions, New Research, Research , , , , , ,

American Obstetrician Takes Rational Position on Home Birth

June 16th, 2015 by avatar

Neel Shah, Harvard Medical School assistant professor and practicing obstetrician, commenting in the New England Journal of Medicine Perspectives section –  “A NICE Delivery – The Cross-Atlantic Divide over Treatment Intensity in Childbirth“, agrees with new United Kingdom National Institute for Health and Care Excellence (NICE) guidelines concluding that healthy, low-risk women are better off at home or in a midwife-led unit than in a hospital under the supervision of an obstetrician. Citing a table comparing outcomes in low-risk multiparous women from the Birthplace in England data, Shah writes:

The safety argument against physician-led hospital birth is simple and compelling: obstetricians, who are trained to use scalpels and are surrounded by operating rooms, are much more likely than midwives to pick up those scalpels and use them. For women giving birth, the many interventions that have become commonplace during childbirth are unpleasant and may lead to complications . . . .

He quite reasonably adds the caveat that the guidelines apply to low-risk women only and that even these women may develop labor complications without warning, but then, responsible home birth advocates acknowledge those same two points. That being said, I can’t resist adding a couple of caveats of my own.

© Families Upon ThamesFirst, one reason why women with risk factors plan home birth, women with prior cesareans being a common example, is that doctors and hospitals deny them the possibility of vaginal birth (Declercq 2013). With their only hospital alternative being unwanted and unneeded cesarean surgery, planned home birth becomes their least, worst option. This dilemma puts their choice squarely in the lap of the medical system. Another reason is that some women have been so emotionally traumatized by their treatment during a previous birth that they reject planned hospital birth and refuse intrapartum transfer even when this may be the safer option (Boucher 2009; Symon 2010). Again, the failure and its remedy lie with the system, not the woman.

Second, if the hospital lacks 24/7 obstetric, anesthesia, and pediatric coverage and at least a Level 2 nursery, which many do, then a woman is probably no better off in the hospital in an emergency than she would be at home or at a freestanding birth center. Furthermore, most urgent situations—a baby who doesn’t breathe, excessive bleeding, even umbilical cord prolapse—can be managed or stabilized by a properly trained and equipped home birth attendant. In fact, what would be done in the hospital is no different from what would be done at home: neonatal resuscitation, oxygen, medications to stop bleeding, maternal knee-chest position and manually holding the fetal head off the cord until cesarean.

Finally, with admirable frankness, Shah notes that unlike the U.K., and to the detriment of safety, “[A]ccess to obstetric care that is coordinated among homes, birthing centers, and hospitals is both unreliable and uncommon.” And while he doesn’t cast any blame, once more, the fault lies with the system. (Just as an FYI, a model guideline for transfer of care developed by a workgroup that included all stakeholders is publically available.)

Shah concludes: “The majority of women with straightforward pregnancies may truly be better off in the United Kingdom.” True that, but it doesn’t have to be that way. Dialing back the overuse of medical intervention and cesarean surgery; respecting the woman’s right to give informed consent and refusal; implementing a culture of care that is kind, compassionate, and respects a woman’s dignity; and ensuring that out-of-hospital birth attendants can consult, collaborate, and transfer care appropriately would have two benefits: it would reduce the number of women refusing hospital birth while minimizing the chance of adverse outcomes in those who continue to prefer to birth at home or in a freestanding birth center. Nonetheless, despite the generally positive responses accompanying Shah’s commentary, rather than inspiring a wave of reform, I would lay odds that the more common reaction to Shah’s piece within the medical community will be to shoot the messenger.

References

Boucher, D., Bennett, C., McFarlin, B., & Freeze, R. (2009). Staying home to give birth: why women in the United States choose home birth. J Midwifery Womens Health, 54(2), 119-126.

Declercq, E., Sakala, C., Corry, M. P., Applebaum, S., & Herrlich, Ariel. (2013). Listening to Mothers III. Pregnancy and Birth. New York: Childbirth Connection.

Symon, A., Winter, C., Donnan, P. T., & Kirkham, M. (2010). Examining autonomy’s boundaries: a follow-up review of perinatal mortality cases in UK independent midwifery. Birth, 37(4), 280-287.

About Henci Goer

© Henci Goer

Henci Goer, award-winning medical writer and internationally known speaker, is the author of The Thinking Woman’s Guide to a Better Birth and Optimal Care in Childbirth: The Case for a Physiologic Approach She is the winner of the American College of Nurse-Midwives “Best Book of the Year” award. An independent scholar, she is an acknowledged expert on evidence-based maternity care.

Evidence Based Medicine, Guest Posts, Home Birth, Maternal Quality Improvement, Maternity Care, Medical Interventions, Midwifery , , , , , ,

Henci Goer – Fact Checking the New York Times Home Birth Debate

February 26th, 2015 by avatar
home birth

© HoboMama

An article in The New York Times Opinion Pages – Room for Debate was released on February 24th, 2015.  As customary in this style of article, the NYT asks a variety of experts to provide essays on the topic at hand, in this case, the safety of home birth. Henci Goer, author and international speaker on maternity care, and an occasional contributor to our blog, takes a look at the facts on home birth and evaluates how they line up with some of the essay statements. Read Henci’s analysis below.  – Sharon Muza, Science & Sensibility Community Manager

As one would predict, three of the four obstetricians participating in the NY Times debate “Is Home Birth Ever a Safe Choice?“assert that home birth is unacceptably risky. Equally predictably, the evidentiary support for their position is less than compelling.

John Jennings, MD president of the American Congress of Obstetricians & Gynecologists, in his response- “Emergency Care Can Be Too Urgently Needed,” cites a 2010 meta-analysis by Wax and colleagues that has been thoroughly debunked. Here is but one of the many commentaries, Meta-Analysis: The Wrong Tool Wielded Improperly, pointing out its weaknesses. In a nutshell, the meta-analysis includes studies in its newborn mortality calculation that were not confined to low-risk women having planned home births with a qualified home birth attendant while omitting a well-conducted Dutch home birth study that dwarfed the others in size and reported equivalent newborn death rates in low-risk women beginning labor at home and similar women laboring in the hospital (de Jonge 2009).

The other naysayers, Grunebaum and Chervenak, in their response – “Home Birth Is Not Safe“, source their support to an earlier NY Times blog post that, in turn, cites a study conducted by the two commentators (and others) (Grunebaum 2014). Their study uses U.S. birth certificate data from 2006 to 2009 to compare newborn mortality (day 1 to day 28) rates at home births attended by a midwife, regardless of qualifications, with births attended by a hospital-based midwife, who almost certainly would be a certified nurse midwife (CNM) in babies free of congenital anomalies, weighing 2500 g or more, and who had reached 37 weeks gestation. The newborn mortality rate with home birth midwives was 126 per 10,000 versus 32 per 10,000 among the hospital midwives, nearly a 4-fold difference. However, as an American College of Nurse-Midwives commentary on the abstract for the Society for Maternal-Fetal Medicine presentation that preceded the study’s publication observed, vital statistics data aren’t reliably accurate, don’t permit confident determination of intended place of birth, and don’t follow transfers of care during labor.

As it happens, we have a study that is accurate and allows us to do both those things. The Midwives Alliance of North America study reports on almost 17,000 planned home births taking place between 2004 and 2009 (Cheyney 2014b), and therefore overlapping Grunebaum and Chervenak’s analysis, in which all but 1000 births (6%) were attended by certified or licensed home birth midwives. According to the MANA stats, the newborn death rate in women who had never had a cesarean and who were carrying one, head-down baby, free of lethal congenital anomalies was 53 per 10,000, NOT 126 per 10,000. This is less than half the rate in the Grunebaum and Chervenak analysis. (As a side note, let me forestall a critique of the MANA study, which is that midwives simply don’t submit births with bad outcomes to the MANA database. In point of fact, midwives register women in the database in pregnancy [Cheyney 2014a], before, obviously, labor outcome could be known. Once enrolled, data are logged throughout pregnancy, labor and birth, and the postpartum, so once in the system, women can’t fall off the radar screen.)

We’re not done. Grunebaum and Chervenak’s analysis suffers from another glaring flaw as well. Using hospital based midwives as the comparison group would seem to make sense at first glance, but unlike the MANA stats, which recorded outcomes regardless of where women ultimately gave birth or who attended them, hospital-based midwives would transfer care to an obstetrician when complications arose. This would remove labors at higher risk of newborn death from their statistics because the obstetrician would be listed on the birth certificate as the attendant, not the midwife. For this reason, the hospital midwife rate of 32 per 10,000 is almost certainly artificially low. So Grunebaum and Chervenak’s difference of 94 per 10,000 has become 21 per 10,000 at most and probably much less than that, a difference that I’d be willing to bet isn’t statistically significant, meaning unlikely to be due to chance. On the other hand, studies consistently find that, even attended by midwives, several more low-risk women per 100 will end up with cesarean surgery—more if they’re first-time mothers—then compared with women planning home births (Romano, 2012).

Hopefully, I’ve helped to provide a defense for those who may find themselves under attack as a result of the NY Times article. I’m not sanguine, though. As can be seen by Jennings, Grunebaum, and Chervenak, people against home birth often fall into the category of “My mind is made up; don’t confuse me with the facts.”

photo source: creative commons licensed (BY-NC-SA) flickr photo by HoboMama: http://flickr.com/photos/44068064@N04/8586579077

References

Cheyney, M., Bovbjerg, M., Everson, C., Gordon, W., Hannibal, D., & Vedam, S. (2014). Development and validation of a national data registry for midwife-led births: the Midwives Alliance of North America Statistics Project 2.0 dataset. J Midwifery Womens Health, 59(1), 8-16. doi: 10.1111/jmwh.12165 http://www.ncbi.nlm.nih.gov/pubmed/24479670

Cheyney, M., Bovbjerg, M., Everson, C., Gordon, W., Hannibal, D., & Vedam, S. (2014b). Outcomes of care for 16,924 planned home births in the United States: the midwives alliance of north america statistics project, 2004 to 2009. J Midwifery Womens Health, 59(1), 17-27. doi: 10.1111/jmwh.12172 http://www.ncbi.nlm.nih.gov/pubmed/24479690

de Jonge, A., van der Goes, B. Y., Ravelli, A. C., Amelink-Verburg, M. P., Mol, B. W., Nijhuis, J. G., . . . Buitendijk, S. E. (2009). Perinatal mortality and morbidity in a nationwide cohort of 529,688 low-risk planned home and hospital births. BJOG 116(9), 1177-1184. http://www.ncbi.nlm.nih.gov/pubmed?term=1177%5Bpage%5D+AND+2009%5Bpdat%5D+AND+de+jonge%5Bauthor%5D&cmd=detailssearch

Grunebaum, A., McCullough, L. B., Sapra, K. J., Brent, R. L., Levene, M. I., Arabin, B., & Chervenak, F. A. (2014). Early and total neonatal mortality in relation to birth setting in the United States, 2006-2009. Am J Obstet Gynecol, 211(4), 390 e391-397. doi: 10.1016/j.ajog.2014.03.047 http://www.ajog.org/article/S0002-9378(14)00275-0/abstract

Romano, A. (2012). The place of birth: home births. In Goer H. & Romano A. (Eds.), Optimal Care in Childbirth: The Case for a Physiologic Approach. Seattle, WA: Classic Day Publishing.

Wax, J. R., Lucas, F. L., Lamont, M., Pinette, M. G., Cartin, A., & Blackstone, J. (2010). Maternal and newborn outcomes in planned home birth vs planned hospital births: a metaanalysis. Am J Obstet Gynecol, 203(3), 243.e241-e248. http://www.ajog.org/article/S0002-9378%2810%2900671-X/abstract

About Henci Goer

Henci Goer

Henci Goer

Henci Goer, award-winning medical writer and internationally known speaker, is the author of The Thinking Woman’s Guide to a Better Birth and Optimal Care in Childbirth: The Case for a Physiologic Approach She is the winner of the American College of Nurse-Midwives “Best Book of the Year” award. An independent scholar, she is an acknowledged expert on evidence-based maternity care.  

 

 

Babies, Evidence Based Medicine, Guest Posts, Home Birth, Maternal Quality Improvement, Maternity Care, Midwifery , , , , ,

Epidurals: Do They or Don’t They Increase Cesareans?

January 27th, 2015 by avatar

By Henci Goer

In October, Author Henci Goer wrote an article for Science & Sensibility, Epidural Anesthesia: To Delay or Not To Delay – That is the Question – examining the impact of the timing of an epidural on labor and birth.  Today Henci looks at some new research, Epidural analgesia in labour and risk of caesarean delivery which seeks to determine whether receiving an epidural at all impacts the likelihood of a cesarean delivery.  Lamaze International has a great infographic on epidurals that you also may find very helpful. – Sharon Muza, Community Manager, Science & Sensibility.

© J. Wasikowski, provided by Birthtastic

© J. Wasikowski, provided by Birthtastic

Let’s start with a bit of background for those of you who didn’t personally live through the early controversy over whether epidurals increased the cesarean rate. As epidurals began to achieve popularity in the late 1970s and 1980s, one researcher sounded the alarm when he and his group published a study of 714 first-time mothers showing that even after excluding women with big babies and women whose labor pattern was abnormal prior to having an epidural, epidurals remained a potent factor in cesarean rates for delayed progress (Thorp 1989). Everyone pooh-poohed his finding on grounds that observational studies can’t truly determine whether epidurals lead to more cesareans or women experiencing more prolonged, painful labors, and therefore at higher risk for cesarean, were more likely to want epidurals. The “chicken versus egg” question, they argued, couldn’t be resolved without a randomized controlled trial (RCT), and it wasn’t likely that women would agree to be assigned by chance to have an epidural or not. In point of fact, that same year saw publication of a small Danish RCT (107 women, 104 of them first-time mothers) (Philipsen 1989). It reported that having an epidural nearly tripled the cesarean rate (16% vs. 6%) for “cephalopelvic disproportion” despite no clinical evidence of CPD being a requirement for inclusion. The investigators ignored this, however, concluding only that instrumental vaginal delivery rates were similar, and epidurals provided better pain relief. In any case, the anesthetic dose was much higher than was already becoming the norm, so it could be reasonably argued that the trial’s findings wouldn’t apply to modern-day practice.

Thorp, meanwhile, took up the RCT challenge. He and his colleagues carried out an epidural versus no epidural trial in 93 first-time mothers and found that epidurals did, in fact, lead to cesareans (25% vs. 2%), not vice versa (Thorp 1993). That bit of unwelcome news precipitated a stampede to perform more RCTs, and when enough of those had accumulated, to a series of systematic reviews pooling their data (meta-analysis), of which the Cochrane review, Anim-Somuah et al. (2011), is the latest. These reached the more comfortable conclusion that epidurals didn’t increase likelihood of cesarean, and pro-epiduralists breathed a collective sigh of relief and went back, if they had ever stopped, to unreservedly recommending epidurals. (This rather sweeps under the rug the other problems epidurals can cause, but that’s a topic for another day.)

Weaknesses of the “Epidural” vs. “No Epidural” Trials

Epidural

By User:Ravedave (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html)

The finding that epidurals don’t increase cesareans is puzzling because they increase likelihood of factors associated with them (Anim-Somuah 2011). For one thing, they increase use of oxytocin to augment labor, which implies they slow labor. For another, more women run fevers, and it stands to reason that a woman progressing slowly who starts running a fever is a likely candidate for cesarean. For a third, the difference in fetal malposition (occiput posterior) rates at delivery comes close to achieving statistical significance, meaning the difference is unlikely to be due to chance. Persistent OP is strongly associated with cesarean delivery (Cheng 2006; Fitzpatrick 2001; Phipps 2014; Ponkey 2003; Senecal 2005; Sizer 2000). Epidurals even increase cesareans for fetal distress by 40%, although the absolute difference didn’t amount to much (1 more per 100 women). Could a difference exist and meta-analysis of RCTs fail to detect it?

A string of well-conducted observational studies over the years have suggested that they could (Eriksen 2011; Kjaergaard 2008; Lieberman 1996; Nguyen 2010), the most recent of which is a very large, very convincing study published last fall (Bannister-Tyrrell 2014). Its authors point out, as have others before them, the weaknesses of the RCTs, weaknesses serious enough to nullify their results or make them inapplicable to typical community practice (external validity).

To begin with, in most trials, substantial percentages of women allocated to the non-epidural group ended up having epidurals, and some women allocated to the epidural group ended up not having one. Since RCTs analyze results according to group assignment (to do otherwise would negate the point of random assignment, which is to avoid bias), not what actually happened, this diminishes differences between groups. In addition, trials were mostly confined to women with no medical or obstetric complications who were treated according to strict protocols for labor management and indications for cesarean delivery. Neither is the case in most hospitals. To these I would add that many trials lumped together first-time mothers and women with prior births when reporting outcomes. First-time mothers are much more susceptible to factors that impede progress, so including women with prior vaginal births can make it appear that epidurals are less problematic for first-time mothers than they really are. In addition, three of the trials were carried out in a hospital where participants were mostly attended by midwives, and cesarean rates were much lower than is common for women attended by obstetricians.

All of this means that any null results in meta-analyses of the trials can be taken with a grain of salt, any findings of significant differences probably represent a minimal value, and first-time moms may be harder hit than appears. To cite one example, Anim-Somuah (2011) reported that 5 more women per 100 having epidurals had a malpositioned baby at delivery (18% vs. 13%) in the 4 trials reporting this outcome, a difference, as I said, that just missed achieving statistical significance. But when I confined results to the two trials in first-time mothers alone in which 10% or fewer of the women in the “no-epidural” group had an epidural, the gap widened to 9 more per 100 (11% vs. 2%).

Summary of the Bannister-Tyrrell (2014) Analysis

Bannister-Tyrrell and colleagues (2014) drew their population from a database of 210,700 Australian women with no prior cesareans who were laboring at term with a singleton, head-down baby. A strength of the database was that, unlike most, it distinguished epidurals for labor from epidurals for delivery. Using a long list of factors, investigators constructed a propensity score for how likely a woman was to have an epidural, matched women according to their score, and compared results according to whether women with the same score had or didn’t have an epidural. Matched controls were found for 52,600 women who had an epidural and were found across the full range of propensity scores. Women having epidurals were 2.5 times more likely to have a cesarean (20% vs. 8%), or put another way, 12 more women per 100 having epidurals had a cesarean (absolute excess), which amounts to 1 additional cesarean for every 8.5 women having an epidural (number needed to harm). Among first-time mothers, women having epidurals were 2.4 times more likely to have a cesarean. Study authors didn’t provide cesarean rates for this subgroup, but the raw cesarean rates overall were 18% in first-time mothers versus 2% in women with prior births, so the effect on this more vulnerable population could be dire.

But there’s still more. Investigators further adjusted for confounding factors not captured in their database. These included differences in health-care settings (same state but not same city), care provider (women without epidurals are more likely to be attended by midwives), and for confounding interventions more likely with epidurals (continuous fetal monitoring). Relative risk of cesarean with an epidural remained at 2.5. Investigators then adjusted for the association between occiput posterior baby and cesarean by setting estimates of the risk ratio to exceed the strongest associations reported in the literature, and they assumed that the prevalence of severe labor pain was 3 to 4 times higher in women having epidurals. Factoring these into their statistical analysis reduced the risk ratio, but women having epidurals still were 50% more likely to have a cesarean. This means that with a baseline cesarean rate of 8% in women without an epidural, 12% of women with an epidural will have one or 4 more women per 100 or 1 more cesarean for every 25 women.

The Take-Home

At the very least we cannot assure women with confidence that epidurals don’t increase the likelihood of cesarean. For this reason and because of their numerous other drawbacks and considering that comfort measures and other strategies have been shown to be both effective for most women and free of adverse effects (Declercq 2006; Jones 2012), women may want to make epidurals Plan B rather than Plan A. That being said, whatever their choice, women can minimize their chance of cesarean—with or without an epidural—by choosing a midwife or doctor whose policies and practices promote spontaneous vaginal birth http://www.lamaze.org/HealthyBirthPractices.

References

Anim-Somuah, M., Smyth, R. M., & Jones, L. (2011). Epidural versus non-epidural or no analgesia in labour. Cochrane Database Syst Rev(12), CD000331. doi: 10.1002/14651858.CD000331.pub3 http://www.ncbi.nlm.nih.gov/pubmed/22161362

Bannister-Tyrrell, M., Ford, J. B., Morris, J. M., & Roberts, C. L. (2014). Epidural analgesia in labour and risk of caesarean delivery. Paediatr Perinat Epidemiol, 28(5), 400-411. http://www.ncbi.nlm.nih.gov/pubmed/25040829

Cheng, Y. W., Shaffer, B. L., & Caughey, A. B. (2006). Associated factors and outcomes of persistent occiput posterior position: A retrospective cohort study from 1976 to 2001. J Matern Fetal Neonatal Med, 19(9), 563-568. http://www.ncbi.nlm.nih.gov/pubmed/16966125?dopt=Citation

Declercq, E., Sakala, C., Corry, M. P., & Applebaum, S. (2006). Listening to Mothers II: Report of the Second National U.S. Survey of Women’s Childbearing Experiences. New York: Childbirth Connection. http://childbirthconnection.org/pdfs/LTMII_report.pdf

Eriksen, L. M., Nohr, E. A., & Kjaergaard, H. (2011). Mode of delivery after epidural analgesia in a cohort of low-risk nulliparas. Birth, 38(4), 317-326. http://www.ncbi.nlm.nih.gov/pubmed/22112332

Fitzpatrick, M., McQuillan, K., & O’Herlihy, C. (2001). Influence of persistent occiput posterior position on delivery outcome. Obstet Gynecol, 98(6), 1027-1031. http://www.ncbi.nlm.nih.gov/pubmed/11755548?dopt=Citation

Jones, L., Othman, M., Dowswell, T., Alfirevic, Z., Gates, S., Newburn, M., . . . Neilson, J. P. (2012). Pain management for women in labour: an overview of systematic reviews. Cochrane Database Syst Rev, 3, CD009234. http://www.ncbi.nlm.nih.gov/pubmed/22419342

Kjaergaard, H., Olsen, J., Ottesen, B., Nyberg, P., & Dykes, A. K. (2008). Obstetric risk indicators for labour dystocia in nulliparous women: a multi-centre cohort study. BMC Pregnancy Childbirth, 8, 45. http://www.ncbi.nlm.nih.gov/pubmed/18837972?dopt=Citation

Lieberman, E., Lang, J. M., Cohen, A., D’Agostino, R., Jr., Datta, S., & Frigoletto, F. D., Jr. (1996). Association of epidural analgesia with cesarean delivery in nulliparas. Obstet Gynecol, 88(6), 993-1000. http://www.ncbi.nlm.nih.gov/pubmed/8942841

Nguyen, U. S., Rothman, K. J., Demissie, S., Jackson, D. J., Lang, J. M., & Ecker, J. L. (2010). Epidural analgesia and risks of cesarean and operative vaginal deliveries in nulliparous and multiparous women. Matern Child Health J, 14(5), 705-712. http://www.ncbi.nlm.nih.gov/pubmed/19760498?dopt=Citation

Philipsen, T., & Jensen, N. H. (1989). Epidural block or parenteral pethidine as analgesic in labour; a randomized study concerning progress in labour and instrumental deliveries. Eur J Obstet Gynecol Reprod Biol, 30(1), 27-33. http://www.ncbi.nlm.nih.gov/pubmed/2924990

Phipps, H., Hyett, J. A., Graham, K., Carseldine, W. J., Tooher, J., & de Vries, B. (2014). Is there an association between sonographically determined occipito-transverse position in the second stage of labor and operative delivery? Acta Obstet Gynecol Scand, 93(10), 1018-1024. http://www.ncbi.nlm.nih.gov/pubmed/25060716

Ponkey, S. E., Cohen, A. P., Heffner, L. J., & Lieberman, E. (2003). Persistent fetal occiput posterior position: obstetric outcomes. Obstet Gynecol, 101(5 Pt 1), 915-920. http://www.ncbi.nlm.nih.gov/pubmed/12738150?dopt=Citation

Senecal, J., Xiong, X., Fraser, W. D., & Pushing Early Or Pushing Late with Epidural study, group. (2005). Effect of fetal position on second-stage duration and labor outcome. Obstet Gynecol, 105(4), 763-772. http://www.ncbi.nlm.nih.gov/pubmed/15802403

Sizer, A. R., & Nirmal, D. M. (2000). Occipitoposterior position: associated factors and obstetric outcome in nulliparas. Obstet Gynecol, 96(5 Pt 1), 749-752. http://www.ncbi.nlm.nih.gov/pubmed/11042312?dopt=Citation

Thorp, J. A., Hu, D. H., Albin, R. M., McNitt, J., Meyer, B. A., Cohen, G. R., & Yeast, J. D. (1993). The effect of intrapartum epidural analgesia on nulliparous labor: a randomized, controlled, prospective trial. Am J Obstet Gynecol, 169(4), 851-858. http://www.ncbi.nlm.nih.gov/pubmed/8238138?dopt=Citation

Thorp, J. A., Parisi, V. M., Boylan, P. C., & Johnston, D. A. (1989). The effect of continuous epidural analgesia on cesarean section for dystocia in nulliparous women. Am J Obstet Gynecol, 161(3), 670-675. http://www.ncbi.nlm.nih.gov/pubmed/2782350

About Henci Goer

Henci Goer

Henci Goer

Henci Goer, award-winning medical writer and internationally known speaker, is the author of The Thinking Woman’s Guide to a Better Birth and Optimal Care in Childbirth: The Case for a Physiologic Approach She is the winner of the American College of Nurse-Midwives “Best Book of the Year” award. An independent scholar, she is an acknowledged expert on evidence-based maternity care.  

 

Cesarean Birth, Childbirth Education, Epidural Analgesia, Guest Posts, Healthy Birth Practices, Medical Interventions, New Research, Pain Management, Research , , , , , , ,

Epidural Analgesia: To Delay or Not to Delay, That Is the Question

October 23rd, 2014 by avatar

By Henci Goer

Unless you have been “off the grid” on a solitary trek, surely you have read and heard the recent flurry of discussion surrounding the just released study making the claim that the timing of when a woman receives an epidural (“early” or “late” in labor) made no difference in the rate of cesarean delivery.  Your students and clients may have been asking questions and wondering if the information is accurate.  Award winning author and occasional Science & Sensibility contributor Henci Goer reviews the 9 studies that made up the Cochrane systematic review: Early versus late initiation of epidural analgesia for labour to determine what they actually said.  Read her review here and share if you agree with all the spin in the media about this new research review. Additionally, head on over to the professional and parent Lamaze International sites to check out the new infographic on epidurals to share with your students and clients.- Sharon Muza, Science & Sensibility Manager. 

Epidural infographic oneArticles have been popping up all over the internet in recent weeks citing a new Cochrane systematic review- Early versus late initiation of epidural analgesia for labour, concluding that epidural analgesia for labor needn’t be delayed because early initiation doesn’t increase the likelihood of cesarean delivery, or, for that matter, instrumental vaginal delivery (Sng 2014). The New York Times ran this piece. Some older studies have found that early initiation appeared to increase likelihood of cesarean (Lieberman 1996; Nageotte 1997; Thorp 1991), which is plausible on theoretical grounds. Labor progress might be more vulnerable to disruption in latent than active phase. Persistent occiput posterior might be more frequent if the woman isn’t moving around, and fetal malposition greatly increases the likelihood of cesarean and instrumental delivery. Which is right? Let’s dig into the review.

The review includes 9 randomized controlled trials of “early” versus “late” initiation of epidural analgesia. Participants in all trials were limited to healthy first-time mothers at term with one head-down baby. Five trials further limited participants to women who began labor spontaneously, three mixed women being induced with women beginning labor spontaneously, and in one, all women were induced. Analgesia protocols varied, but all epidural regimens were of modern, low-dose epidurals. So far, so good.

Examining the individual trials, though, we see a major problem. You would think that the reviewers would have rejected trials that failed to divide participants into distinct groups, one having epidural initiation in early labor and the other in more advanced labor, since the point of the review is to determine whether early or late initiation makes a difference. You would think wrong. Of the nine included trials, six failed to do this.

cc photo bryanrmason http://flickr.com/photos/b-may/397189835

cc photo bryanrmason http://flickr.com/photos/b-may/397189835

The two Chestnut trials (1994a; 1994b) had the same design, differing only in that one was of women who were laboring spontaneously at trial entry and the other included women receiving oxytocin for induction or augmentation. Women were admitted to the trial if they were dilated between 3 and 5 cm. Women in the early group got their epidural immediately while women in the late group could have an epidural only if they were dilated to 5 cm or more. If late-group women were not dilated to 5 cm, they were given systemic opioids and could have a second dose of opioid one hour later. They could have an epidural when they attained 5 cm dilation or regardless of dilation, an hour after the second opioid dose. Let’s see how that worked out.

Among the 149 women in the trial that included women receiving oxytocin (Chestnut 1994b), median dilation in the early group at time of epidural initiation was 3.5 cm, meaning that half the women were dilated more and half less than this amount. The interquartile deviation was 0.5 cm, which means that values were fairly tightly clustered around the median. The authors state, however, that cervical dilation was assessed using 0.5 increments which meant that dilation of 3-4 cm was recorded as 3.5. In other words, women in the early group might have been dilated to as much as 4 cm. The median dilation in the late group was 5.0 cm, again with a 0.5 cm interquartile deviation. Some women in the late group, therefore, were not yet dilated to 5 cm when their epidural began, and, in fact, the authors report that 26 of the 75 women (35%) in the late group were given their epidural after the second dose of opioid but before attaining 5 cm dilation. The small interquartile deviation in the late group tells us that few, if any, women would have been dilated much more than 5 cm. Add in that assessing dilation isn’t exact, so women might have been a bit more or less dilated than they were thought to be, and it becomes clear that the “early” and “late” groups must have overlapped considerably. Furthermore, pretty much all of them were dilated between 3 and 5 cm when they got their epidurals, which means that few of these first-time mothers would have been in active labor, as defined by the new ACOG standards.

Overlap between early and late groups must have been even greater in Chestnut et al.’s (1994a) trial of 334 women laboring spontaneously at trial entry because median dilation in the early group was greater than in the other trial (4 cm, rather than 3.5) while median dilation in the late group was the same (5.0 cm), and interquartile deviation was even tighter in the late group (0.25 cm, rather than 0.5 cm). As before, dilation was measured in 0.5 cm increments, which presumably means that women in the early group dilated to 4-5 cm would have been recorded as “4.5,” thereby qualifying them for the “early” group even though they might have been as much as 5 cm dilated.

Based on my analysis, I would argue that there was no clinically meaningful difference in dilation between early and late groups in either trial.

A second pair of trials, one a mixed trial of spontaneous labor onset and induction and the other all induced, also had the same design in both trials (Wong 2005; Wong 2009). All women were less than 4 cm dilated at first request for pain medication. In the early group, women had an opioid injected intrathecally, i.e. the “spinal” part of a combined spinal-epidural, and an epidural catheter was set. At the second request, an epidural was initiated. In the late group, women were given a systemic opioid. At second request, they were given a second dose of systemic opioid if they hadn’t reached 4 cm dilation and an epidural if they had dilated to 4 cm or more. At third request, they were given an epidural regardless of dilation. Women who had no vaginal exam at second request and were given an epidural were “assumed,” in the authors’ words, to be dilated to at least 4 cm. What were the results?

Wong (2005) included 728 women, some beginning labor spontaneously and some induced. You may already have noticed the flaw in the trials’ design: Wong and colleagues confused the issue by considering intrathecal opioid to be equivalent to epidural anesthetic in the early group, although women didn’t actually receive anesthetic until their second request for pain medication some unknown time later. So far as I know we have no evidence that opiods, spinal or epidural, have any effect on labor progress. As to dilation at the time of epidural initiation, 63% of women in the so-called “early” group were either determined or assumed to be at 4 cm dilation or more while in the late group, some unknown proportion were less than 4 cm dilated either because they got their epidural at third pain medication request regardless of dilation or they were assumed to be at 4 or more cm dilation at second request, but weren’t assessed.

Wong (2009), a study of 806 induced women, was set up the same way but reported data somewhat differently. Early-group women were administered a spinal opioid at a median of 2 cm dilation and an interquartile range of 1.5 to 3 cm, which means that values in the middle 50% of the dataset ranged from 1.5 to 3 cm. We have no information on dilation at the time they received their epidural. The median dilation at which late-group women had their epidural initiated was 4 cm with an interquartile range of 3 to 4 cm, that is, in the middle 50% of the dataset ranged from 3 to 4 cm dilation.

As with the Chestnut trials, dilation at time of epidural initiation in the two Wong trials must have overlapped considerably between groups. And, again, few women in the late epidural group would have been in active labor. The Wong trials, however, muddy the waters even further by considering spinal opioid to be the same thing as epidural anesthetic, and while the authors were careful to use the term “neuraxial analgesia,” the Cochrane reviewers made no such distinction.

This brings us to Parameswara (2012), a trial of 120 women that included both spontaneous onset and induced labors. This trial defined the early group as women less than 2 cm dilated at time of epidural initiation and the late group as women more than 2 cm dilated. That’s all the information they provide on group allocation.

Last of the six, we have Wang (2011), a trial of 60 women in spontaneous labor. All women were given intrathecal anesthetic plus opioid. The early group was started on epidural anesthetic plus opioid 20 minutes later whereas the late group had their epidural initiated when they requested additional pain relief. No information is given on dilation at time of epidural initiation. Not only do we have no idea whether early and late groups differed from one another, women in both groups received neuraxial anesthetic at the same time.

In summary, “garbage in, garbage out.” No conclusions can be drawn about the effect of early versus late epidural administration from these six studies.

The other three studies are a different story. They achieve a reasonable separation between groups. Luxman (1998) studied 60 women with spontaneous labor onset. The early group had a mean, i.e., average, dilation of 2.3 cm with a standard deviation of + or – 0.6 cm while the late group had a mean dilation of 4.5 cm + or – 0.2 cm. Ohel (2006) studied a mixed spontaneous onset and induced group of 449 women. The mean dilation at initiation in the early group was 2.4 cm with a standard deviation of 0.7 cm, and the late group had a mean dilation of 4.6 cm with a standard deviation of 1.1 cm. Wang (2009), the behemoth of the trials, included 12,629 women who began labor spontaneously. The early epidural group had a median dilation of 1.6 cm with an interquartile range of 1.1 to 2.8 and the late group a median of 5.1 cm dilation with an interquartile range of 4.2 to 5.7. Cesarean and instrumental delivery rates were similar between early and late groups in all three trials, so had reviewers included only these three trials, they would still have arrived at the same conclusion: early epidural initiation doesn’t increase likelihood of cesarean and instrumental delivery.

We’re not done, though. Wang (2009) points us to a second, even bigger issue.

The Wang (2009) trial, as did all of the trials, limited participants to healthy first-time mothers with no factors that would predispose them to need a cesarean. The Wang trial further excluded women who didn’t begin labor spontaneously. Nevertheless, the cesarean rate in these ultra-low-risk women was an astonishing 23%. Comparing the trials side-by-side reveals wildly varying cesarean and instrumental vaginal delivery rates in what are essentially homogeneous populations.

© Henci Goer

© Henci Goer

© Henci Goer

© Henci Goer

Comparing the trials uncovers that epidural timing doesn’t matter because any effect will be swamped by the much stronger effect of practice variation.

Analysis of the trials teaches us two lessons: First, systematic reviews can’t always be taken at face value because results depend on the beliefs and biases that the reviewers bring to the table. In this case, they blinded reviewers from seeing that two-thirds of the trials they included weren’t measuring two groups of women, one in early- and one in active-phase labor. Second, practice variation can be an unacknowledged and potent confounding factor for any outcome that depends on care provider judgment.

Conclusion

So what’s our take home? Women need to know that with a judicious care provider who strives for spontaneous vaginal birth whenever possible, early epidural administration won’t increase odds of cesarean or instrumental delivery. With an injudicious one, late initiation won’t decrease them. That being said, there are other reasons to delay an epidural. Maternal fever is associated with epidural duration. Running a fever in a slowly progressing labor could tip the balance toward cesarean delivery as well as have consequences for the baby such as keeping the baby in the nursery for observation, testing for infection, or administering prophylactic IV antibiotics. Then too, a woman just might find she can do very well without one. Epidurals can have adverse effects, some of them serious. Comfort measures, cognitive strategies, and all around good emotionally and physically supportive care don’t. Hospitals, therefore, should make available and encourage use of a wide range of non-pharmacologic alternatives and refrain from routine practices that increase discomfort and hinder women from making use of them. Only then can women truly make a free choice about whether and when to have an epidural.

After reading Henci’s review and the study, what information do you feel is important for women to be aware of regarding epidural use in labor?  What will you say when asked about the study and timing of an epidural?  You may want to reference a previous Science & Sensibility article by Andrea Lythgoe, LCCE, on the use of the peanut ball to promote labor progress when a woman has an epidural. – SM 

References

Caughey, A. B., Cahill, A. G., Guise, J. M., & Rouse, D. J. (2014). Safe prevention of the primary cesarean delivery. American journal of obstetrics and gynecology210(3), 179-193.

Chestnut, D. H., McGrath, J. M., Vincent, R. D., Jr., Penning, D. H., Choi, W. W., Bates, J. N., & McFarlane, C. (1994a). Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor? Anesthesiology, 80(6), 1201-1208. http://www.ncbi.nlm.nih.gov/pubmed/8010466?dopt=Citation

Chestnut, D. H., Vincent, R. D., Jr., McGrath, J. M., Choi, W. W., & Bates, J. N. (1994b). Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are receiving intravenous oxytocin? Anesthesiology, 80(6), 1193-1200. http://www.ncbi.nlm.nih.gov/pubmed/8010465?dopt=Citation

Lieberman, E., Lang, J. M., Cohen, A., D’Agostino, R., Jr., Datta, S., & Frigoletto, F. D., Jr. (1996). Association of epidural analgesia with cesarean delivery in nulliparas. Obstet Gynecol, 88(6), 993-1000. http://www.ncbi.nlm.nih.gov/pubmed/8942841

Luxman, D., Wolman, I., Groutz, A., Cohen, J. R., Lottan, M., Pauzner, D., & David, M. P. (1998). The effect of early epidural block administration on the progression and outcome of labor. Int J Obstet Anesth, 7(3), 161-164. http://www.ncbi.nlm.nih.gov/pubmed/15321209?dopt=Citation

Nageotte, M. P., Larson, D., Rumney, P. J., Sidhu, M., & Hollenbach, K. (1997). Epidural analgesia compared with combined spinal-epidural analgesia during labor in nulliparous women. N Engl J Med, 337(24), 1715-1719. http://www.ncbi.nlm.nih.gov/pubmed/9392696?dopt=Citation

Ohel, G., Gonen, R., Vaida, S., Barak, S., & Gaitini, L. (2006). Early versus late initiation of epidural analgesia in labor: does it increase the risk of cesarean section? A randomized trial. Am J Obstet Gynecol, 194(3), 600-605. http://www.ncbi.nlm.nih.gov/pubmed/16522386?dopt=Citation

Parameswara, G., Kshama, K., Murthy, H. K., Jalaja, K., Venkat, S. (2012). Early epidural labour analgesia: Does it increase the chances of operative delivery? British Journal of Anaesthesia 108(Suppl 2):ii213–ii214. Note: This is an abstract only so all data from it come from the Cochrane review.

Sng, B. L., Leong, W. L., Zeng, Y., Siddiqui, F. J., Assam, P. N., Lim, Y., . . . Sia, A. T. (2014). Early versus late initiation of epidural analgesia for labour. Cochrane Database Syst Rev, 10, CD007238. doi: 10.1002/14651858.CD007238.pub2 http://www.ncbi.nlm.nih.gov/pubmed/25300169

Thorp, J. A., Eckert, L. O., Ang, M. S., Johnston, D. A., Peaceman, A. M., & Parisi, V. M. (1991). Epidural analgesia and cesarean section for dystocia: risk factors in nulliparas. Am J Perinatol, 8(6), 402-410. http://www.ncbi.nlm.nih.gov/pubmed/1814306?dopt=Citation

Wang, F., Shen, X., Guo, X., Peng, Y., & Gu, X. (2009). Epidural analgesia in the latent phase of labor and the risk of cesarean delivery: a five-year randomized controlled trial. Anesthesiology, 111(4), 871-880. http://www.ncbi.nlm.nih.gov/pubmed/19741492?dopt=Citation

Wang, L. Z., Chang, X. Y., Hu, X. X., Tang, B. L., & Xia, F. (2011). The effect on maternal temperature of delaying initiation of the epidural component of combined spinal-epidural analgesia for labor: a pilot study. Int J Obstet Anesth, 20(4), 312-317. http://www.ncbi.nlm.nih.gov/pubmed/21840705

Wong, C. A., McCarthy, R. J., Sullivan, J. T., Scavone, B. M., Gerber, S. E., & Yaghmour, E. A. (2009). Early compared with late neuraxial analgesia in nulliparous labor induction: a randomized controlled trial. Obstet Gynecol, 113(5), 1066-1074. http://www.ncbi.nlm.nih.gov/pubmed/19384122?dopt=Citation

Wong, C. A., Scavone, B. M., Peaceman, A. M., McCarthy, R. J., Sullivan, J. T., Diaz, N. T., . . . Grouper, S. (2005). The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med, 352(7), 655-665. http://www.ncbi.nlm.nih.gov/pubmed/15716559?dopt=Citation

About Henci Goer

Henci Goer

Henci Goer

Henci Goer, award-winning medical writer and internationally known speaker, is the author of The Thinking Woman’s Guide to a Better Birth and Optimal Care in Childbirth: The Case for a Physiologic Approach She is the winner of the American College of Nurse-Midwives “Best Book of the Year” award. An independent scholar, she is an acknowledged expert on evidence-based maternity care.  

Cesarean Birth, Childbirth Education, Epidural Analgesia, Guest Posts, informed Consent, Medical Interventions, New Research, Systematic Review , , , , , , ,

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