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Does Epidural Analgesia Predispose to Persistent Occiput Posterior?

February 14th, 2013 by avatar

Photo by Patti Ramos Photography

In my January Science and Sensibility blog post, I answered the question “Can We Prevent Persistent Occiput Posterior?” but because it wasn’t relevant to the study that prompted the post, and the piece was already long, I didn’t look at the role of epidural analgesia. Let me now rectify that.

All five studies examining the relationship between epidural analgesia and persistent occiput posterior (OP) find an association between them. Three studies compared women with an epidural versus no epidural according to whether they had an OP baby at delivery and found that 4 to 10 more women per 100 having an epidural had an OP baby at delivery (Cheng, 2006; Lieberman, 2005; Sizer, 2000). The other two compared women with an OP baby at delivery according to whether they had an epidural and found that 13 and 27 more women per 100 with a persistent OP baby had an epidural (Fitzpatrick, 2001; Ponkey, 2003).

Their results, however, aren’t sufficient to convict epidurals because we can’t tell whether having an epidural led to persistent OP or more painful and prolonged OP labor led to having an epidural. Investigators in one of the five studies argued for OP labor coming first on the grounds that while epidurals were more common in women with an OP baby at delivery than in women with an OA baby at delivery (74% vs. 47%) at their institution, a rise in epidural use from 3% in 1975 to 47% in 1998 had, if anything, decreased the hospital’s overall rate of persistent OP (4% vs. 2%) (Fitzpatrick, 2001). This must mean that as epidurals became more freely available, women having difficult OP labors were more likely to opt for one. Epidurals were the result, not the cause, of persistent OP. On the other hand, we have some corroborating evidence for their guilt. For one thing, back pain is thought to be a major reason why women with OP babies are more likely to want epidurals, but it turns out that back pain isn’t unique to OP. Serial sonograms reveal that virtually identical percentages of women laboring with an OA baby report back pain (Lieberman, 2005). For another, three of the five studies took into account other factors associated with difficult labor such as labor induction, labor augmentation, and birth weight and still found that epidurals were an independent risk factor for persistent OP (Cheng, 2006; Lieberman, 2005; Sizer, 2000).

Nevertheless, evidence from observational studies isn’t strong enough to close the case. As I noted, observational studies can determine association but not causation. In addition, investigators may not be able to identify all the confounding and correlating factors that affect outcomes. For a more definitive answer, we need experimental studies. This brings us to randomized controlled trials (RCTs), in which participants are randomly allocated to one form of treatment or the other, and to meta-analysis of RCTs, in which statistical techniques are used to pool data from more than one trial.

The Cochrane systematic review of epidural versus no epidural in labor pools data from four RCTs (673 women overall) that reported on persistent OP (Anim-Somuah, 2011). Five more women per 100 assigned to the epidural group had a persistent OP baby, but meta-analysis found that the difference just missed achieving statistical significance. The risk ratio was 1.4, meaning a 40% increased risk of persistent OP in women assigned to the epidural group compared with women assigned to the no-epidural group, but the 95% confidence interval ranged from 1.0 to 2.0, meaning a 95% probability that the true value lies between no increase (ratio of 1:1) and double the risk (2.0). However, a problem with the RCTs of epidural versus no epidural is that substantial percentages of women assigned to the no-epidural group actually had epidurals, but, as is prescribed in RCT data analysis, they were kept in their original group. In two of the four trials (204 women), though, 10% or less of women assigned to the no-epidural group had epidurals. If we calculate the excess rate of persistent OP in these two trials, we find that the gap widens to 9 more women per 100 with epidurals having a persistent OP baby. We don’t know whether this difference would achieve statistical significance, but the fact that the excess is in the same range as reported in the observational studies (4 to 10 more per 100) gives confidence in its validity.

Patti Ramos Photography

We also have two studies that suggest that the timing of the epidural may matter. One, of 320 women, reports that, after controlling for age, induction of labor, and birth weight, initiating an epidural at fetal station less than zero (above the ischial spines) resulted in 16 more women having a persistent OP or occiput transverse (OT) baby compared with initiation at 0 station or greater (at or lower than the ischial spines), an excess that rose to 20 more per 100 in first time mothers (Robinson, 1996). The other study analyzed outcomes in 500 first-time mothers according to whether an epidural was administered early (at or before 5 cm dilation), late (after 5 cm dilation), or not at all (Thorp, 1991). Seventeen more women per 100 in the early group had a persistent OP or OT baby compared with women in the late-epidural group, and 12 more had a persistent OP or OT baby compared with the no-epidural group, but rates were similar in women in the late and no epidural groups.

Taken all together, we may not have absolute proof of epidural culpability in predisposing to OP, but if I were on the jury, I would vote them “guilty as charged.”

Take home: Even without certainty, the precautionary principle dictates recommending to women desiring an epidural that they use other measures to cope with labor pain until they enter active labor and until it seems clear that positioning and activities are not putting a slow labor on track.

What do you tell your clients, students and patients about the impact on fetal positioning in labor and birth?  Will having this information change what you say?  Let us know in the comments section.

References

Anim-Somuah, M., Smyth, R. M., & Jones, L. (2011). Epidural versus non-epidural or no analgesia in labour. Cochrane Database of Systematic Reviews(12), CD000331.

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. Journal of Maternal Fetal and Neonatal Medicine, 19(9), 563-568.

Fitzpatrick, M., McQuillan, K., & O’Herlihy, C. (2001). Influence of persistent occiput posterior position on delivery outcome. Obstetrics and Gynecology, 98(6), 1027-1031.

Lieberman, E., Davidson, K., Lee-Parritz, A., & Shearer, E. (2005). Changes in fetal position during labor and their association with epidural analgesia. Obstetrics and Gynecology, 105(5 Pt 1), 974-982.

Ponkey, S. E., Cohen, A. P., Heffner, L. J., & Lieberman, E. (2003). Persistent fetal occiput posterior position: obstetric outcomes. Obstetrics and Gynecology, 101(5 Pt 1), 915-920. 

Robinson, C. A., Macones, G. A., Roth, N. W., & Morgan, M. A. (1996). Does station of the fetal head at epidural placement affect the position of the fetal vertex at delivery? American Journal of Obstetrics and Gynecology, 175(4 Pt 1), 991-994.

Sizer, A. R., & Nirmal, D. M. (2000). Occipitoposterior position: associated factors and obstetric outcome in nulliparas. Obstetrics and Gynecology, 96(5 Pt 1), 749-752.

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. American Journal of Perinatology, 8(6), 402-410.

Childbirth Education, Epidural Analgesia, Evidence Based Medicine, Guest Posts, informed Consent, Medical Interventions, Pain Management, Research , , , , , , ,

  1. avatar
    Dreamy
    February 14th, 2013 at 05:34 | #1

    Apologies if I missed it, but is the best guess here that it is the epidural’s necessary limitation of movement that may lead to persistent OP?

  2. avatar
    Dawn
    February 14th, 2013 at 07:26 | #2

    Have had several babies be OP (i’m a mom of 8…my first was turned just before birth…4th was possibly OP as she came quick and my hubs says she was facing up on the bed, my 6th was OP until just before she crowned, 7th born in the OP position and the 8th had been OP until likely 20 minutes before birth when he turned). No epidurals.

  3. February 14th, 2013 at 08:01 | #3

    This article and it’s information doesn’t change what I tell my clients, but backs it up. When I have a client desiring an epidural or “on the fence” about the epidural, I talk to them about the benefits and risks. Point them to more information on the benefits and risks and talk to them about the benefits of waiting until active labor. One thing I make I would like to point out that the article doesn’t seem to address is the sometimes a key factor in movement. Epidurals drastically limit movement for many women and so there is very little a woman can do to help resolve issues with positioning and upright movement.

  4. avatar
    Erinn
    February 14th, 2013 at 08:20 | #4

    I plug Spinning Babies with my clients. One workshop with Gail Tully, and your world is forever changed.

  5. February 14th, 2013 at 08:39 | #5

    @ Dreamy, Patrice, and Erinn
    The relationship between persistent OP and maternal positioning and activity in late pregnancy and in labor was discussed in my previous post and in the follow-on comments. There is a link to that post in the first line of this one.

  6. avatar
    Bree
    February 14th, 2013 at 09:45 | #6

    I find the Lieberman study interesting. As a doula and on L&D rotations (I’m a senior nursing student working towards being a midwife) I have never seen a mama with back labor OP. When I have time (like next year!) I am going to have to follow up on that one as it goes against my own experience and all anecdotal evidence I’ve heard from other doulas and midwives. Is there a distinction drawn between back labor and back pain during labor? See, this is why I love science! Thank you for the excellent post!

  7. avatar
    Lauren Hickman
    February 14th, 2013 at 10:30 | #7

    While this research is important and interesting, I would be more interested to compare the final outcome. Are women who have an epidural with an OP baby more likely to have a cesarean because they are unable to use a variety of positions for pushing?

  8. February 14th, 2013 at 13:51 | #8

    I tell my students and patients to wait for 5 cm and good established labor prior to epidural. I also recommend Gail Tully’s work on spinning babies.com for pre labor pelvic release maneuvers. 27 years ago my first baby was persistent OP and turned after a 15 hour active labor and 3 hours of pushing without an epidural. As a L&D nurse, persistent OP babies are a thorn in my side and a major cause of c/section. Thank you for the article. I will share it with my students.

  9. February 14th, 2013 at 22:00 | #9

    @Lauren
    I don’t know what the specific mechanism is, but I’m also not sure what it would add to pinpoint it. It wouldn’t change the take home. I would still recommend avoiding or at least delaying an epidural. I’d also still recommend trying various pushing positions, epidural or not. Even with an epidural, women can push side lying and many can get onto hands and knees or even squat with assistance. Finally, as I discussed in the previous post, manual rotation can save the day regardless of whether the woman has an epidural.

  10. avatar
    Becky
    February 15th, 2013 at 06:25 | #10

    As a doula, I have had situations where the mom would have liked to do other positions, while on the epidural, but staff absolutely will NOT let her try, due to “safety concerns, our insurance wong let us let you blah blah blah…”, then due to lack of progress or signs of fetal distress they “need” to section. Ugh!

  11. avatar
    Dawn
    February 15th, 2013 at 06:32 | #11

    You know Henci, the persistent OP I did deliver was that way likely due to the cord since it was double wrapped and the midwive did try to move me. Also, the cord did shorted her time inside as she had a drop off of heartrate (I heard it) and I pushed hard to get her out. OP and tilted head as it was born. Midwife reported tight cord, and she even manually tried to move the baby who kept resetting OP (I could feel the body move and move back). But my 8th baby moved out of OP 100% because of position. The midwife allowed me to push in any position, and had me leaning over the back of the bed (almost hands/knees but not quite). I pushed side to side with bed in a semi-recline. I did this sponaneously, left, then right…then left again. She charted his malposition (I allowed a few checks), and then he was born in the easiest position, and it was so easy compared to my OP born!
    I could feel him move off my spine when I did the forward lean, the contractions were better, the back pain was less. It was amazing.

  12. February 15th, 2013 at 08:30 | #12

    @Becky
    Yeah, I know. I’ve sometimes thought of writing a piece on the ways medical management causes the very problems it is supposed to prevent. Rupturing membranes to “get the show on the road,” i.e., reduce the likelihood of cesarean for slow progress, probably increases it. Inducing labor to get a big baby delivered before it grows too big or results in a shoulder dystocia also increases likelihood of labor ending in a cesarean and doesn’t reduce shoulder dystocia. One wonders how many babies whose mothers were induced for reasons suggesting that the baby was compromised would have done just fine with normal labor but couldn’t tolerate the extra stress of induced contractions. And let’s not forget midline episiotomy, which far from protecting the anal sphincter promotes anal sphincter tears.

  13. February 15th, 2013 at 08:36 | #13

    @Dawn
    Your and Betsy’s posts illustrate a fundamental and frustrating problem with the research. We don’t know what outcomes would (or should) be because most of it takes place in a medical-model management environment.

  14. February 15th, 2013 at 09:49 | #14

    Henci,
    In my practice I encourage women to avoid epidural use because they increase risk, period. If they didn’t, we wouldn’t need to have an IV or use continuous EFM when a woman is using one. That said, I recognize that it is my role to work certain risk factors into my practice and mitigate them. My big concern with all “epidural” research out there is that “Epidural” is not a drug, it is a “Route of Entry” it is simply the location and manner of which the actual drugs enter the body. No one would ever do research on the benefits of IM or PO, or even IV. They would research the actual drug entering the body. No two CRNA’s that I’ve worked with (and I’ve worked with them all over the world), have ever used the exact same cocktail of medications in their epidurals. The change the concentration, the rates, and even the basic drugs to fit the situation they are faced with. So until epidural studies begin to control for the Marcaine/Fentanyl vs. Bupivicaine/Duramorph epidural I will always look at such studies with skepticism.
    Tom Johnston
    CNM, IBCLC

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