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Can We Prevent Persistent Occiput Posterior Babies?

January 29th, 2013 by avatar

Today, regular contributor Henci Goer, co-author of the recent book, Optimal Care in Childbirth; The Case for a Physiologic Approach, discusses a just published study on resolving the OP baby during labor through maternal positioning.  Does it matter what position the mother is in?  Can we do anything to help get that baby to turn?  Henci lets us know what the research says in today’s post. – Sharon Muza, Community Manager

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In OP position, the back (occiput) of the fetal head is towards the woman’s back (posterior). Sometimes called “sunny side up,” there is nothing sunny about it. Because the deflexed head presents a wider diameter to the cervix and pelvic opening, progress in dilation and descent tends to be slow with an OP baby, and if OP persists, it greatly increases the likelihood of cesarean or vaginal instrumental delivery and therefore all the ills that follow in their wake.

Does maternal positioning in labor prevent persistent OP?

This month, a study titled “Is maternal posturing during labor efficient in preventing persistent occiput posterior position? A randomized control trial” reported on the use of maternal positioning in labor to rotate OP babies to occiput anterior (OA). Investigators randomly allocated 220 laboring women with OP babies either to assume positions designed to facilitate rotation or to recline on their backs. The positions were devised based on computer modeling of the mechanics of the woman’s pelvis and fetal head according to degree of fetal descent. The position prescribed for station -5 to -3, i.e., 3-5 cm above the ischial spines, a pelvic landmark, had the woman on her knees supporting her head and chest on a yoga ball. At station -2 to 0, i.e., 2 cm above to the level of the ischial spines, she lay on her side on the same side as the fetal spine with the underneath leg bent, and at station > 0, i.e., below the ischial spines, she lay on her side on the same side as the fetal spine with the upper leg bent at a 90 degree angle and supported in an elevated position.

http://flic.kr/p/9Rs7mL

 

The good news is that regardless of group assignment, and despite virtually all women having an epidural (94-96%), 76-78% of the babies eventually rotated to OA. The bad news is that regardless of group assignment, 22-24% of the babies didn’t. As one would predict, 94-97% of women whose babies rotated to OA had spontaneous vaginal births compared with 3-6% of women with persistent OP babies. Because positioning failed to help, investigators concluded: “We believe that no posture should be imposed on women with OP position during labor” (p. e8). 

Leaving aside the connotations of “imposed,” does this disappointing result mean that maternal positioning in labor to correct OP should be abandoned? Maybe not.

Of the 15 women with the fetal head high enough to begin with position 1, no woman used all 3 positions because 100% of them rotated to OA before fetal descent dictated use of position 3. I calculated what percentage of women who began with position 2 or 3, in other words fetal head at -2 station or lower, achieved an OA baby and found it to be 75%—the same percentage as when nothing was done. What could explain this? One explanation is that a position with belly suspended is more efficacious regardless of fetal station, another is that positioning is more likely to succeed before the head engages in the pelvis, and, of course, it may be a combination of both.

Common sense suggests that the baby is better able to maneuver before the head engages in the pelvis. If so, it seem likely that rupturing membranes would contribute to persistent OP by depriving the fetus of the cushion of forewaters and dropping the head into the pelvis prematurely. Research backs this up. A literature search revealed a study, “Associated factors and outcomes of persistent occiput posterior position: A retrospective cohort study from 1976 to 2001“ finding that artificially ruptured membranes was an independent risk factor for persistent OP. Returning to the trial, all women had ruptured membranes because it was an inclusion factor. One wonders how much better maternal positioning might have worked had this not been the case, and an earlier trial offers a possible answer.

In the earlier trial, “Randomized control trial of hands-and-knees position for occipitoposterior position in labor,” half the women had intact membranes. Women in the intervention group assumed hands-and-knees for at least 30 minutes during an hour-long period while the control group could labor in any position other than one with a dependent belly. Twelve more women per 100 had an OA baby at delivery, a much bigger difference than the later trial. Before we get too excited, though, the difference did not achieve statistical significance, meaning results could have been due to chance. Still, this may have been because the population was too small (70 intervention-group women vs. 77 control-group women) to reliably detect a difference, but the trial has a bigger problem: fetal head position at delivery wasn’t recorded in 14% of the intervention group and 19% of the control group, which means we don’t know the real proportions of OA to OP between groups.

Take home: It looks like rupturing membranes may predispose to persistent OP and should be avoided for that reason. The jury is still out on whether a posture that suspends the belly is effective, but it is worth trying in any labor that is progressing slowly because it may help and doesn’t hurt.

Does maternal positioning in pregnancy prevent OP labors?

Some have proposed that by avoiding certain postures in late pregnancy, doing certain exercises, or both, women can shift the baby into an OA position and thereby avoid the difficulties of labor with an OP baby. A “randomized controlled trial of effect of hands and knees posturing on incidence of occiput posterior position at birth (2547 women) has tested that theory. Beginning in week 37, women in the intervention group were asked to assume hands-and-knees and do slow pelvic rocking for 10 minutes twice daily while women in the control group were asked to walk daily. Compliance was assessed through keeping a log. Identical percentages (8%) of the groups had an OP baby at delivery.

Why didn’t this work? The efficacy of positioning and exercise in pregnancy is predicated on the assumption that if the baby is OA at labor onset, it will stay that way. Unfortunately, that isn’t the case. A  study, “Changes in fetal position during labor and their association with epidural anesthesia,” examined the effect of epidural analgesia on persistent OP by performing sonograms on 1562 women at hospital admission, within an hour after epidural administration (or four hours after admission if no epidural had been administered), and after 8 cm dilation. A byproduct was the discovery that babies who were OA at admission rotated to OP as well as vice versa.

Take home: Prenatal positioning and exercises aimed at preventing OP in labor don’t work. Women should not be advised to do them because they may wrongly blame themselves for not practicing or not practicing enough should they end up with a difficult labor or an operative delivery due to persistent OP.

Do we have anything else?

Larry P Howell aafp.org/afp/2007/0601/p1671.html

We do have one ray of sunshine in the midst of this gloom. Three studies of manual rotation (near or after full dilation, the midwife or doctor uses fingers or a hand to turn the fetus to anterior) report high success rates and concomitant major reductions in cesarean rates, if not much effect on instrumental vaginal delivery rates. One study, “Manual rotation in occiput posterior or transverse positions: risk factors and consequences on the cesarean delivery rate,” comparing successful conversion to OA with failures reported an overall institutional success rate of 90% among 796 women. A “before and after” study, “Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section,” reported that before introducing the technique, among 30 women with an OP baby in second stage, 85% of the babies were still OP at delivery compared with 6% of 31 women treated with manual rotation. The cesarean rate was 23% in the “before” group versus 0% in the “after” group. The third study, “Manual rotation to reduce caesarean delivery in persistent occiput posterior or transverse position,” compared 731 women having manual rotation of an OP baby in second stage with 2527 women having expectant management. The success rate of manual rotation was 74% and the overall cesarean rate in treated women was 9% versus 42% in the expectantly managed group.

Manual rotation is confirmed as effective, but is it safe? This last study reported similar rates of acidemia and delivery injury in newborns. As for their mothers, investigators calculated that four manual rotations would prevent one cesarean. The study also found fewer anal sphincter injuries and cases of chorioamnionitis. The only disadvantage was that one more woman per hundred having manual rotation would have a cervical laceration.Take home: Birth attendants should be trained in performing manual rotation, and it should be routine practice in women reaching full dilation with an OP baby.

What has been your experience with the OP baby?  Is what you are teaching and telling mothers in line with the current research?  Will you change what you say now that you have this update?  Share your thoughts in the comment section. – SM

References and resources

Cheng, Y. W., 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 Medicine19(9), 563-568.

Desbriere R, Blanc J, Le Dû R, et al. Is maternal posturing during labor efficient in preventing persistent occiput posterior position? A randomized controlled trial. Am J Obstet Gynecol 2013;208:60.e1-8. PII: S0002-9378(12)02029-7 doi:10.1016/j.ajog.2012.10.882

Kariminia, A., Chamberlain, M. E., Keogh, J., & Shea, A. (2004). Randomised controlled trial of effect of hands and knees posturing on incidence of occiput posterior position at birth. bmj328(7438), 490.

Le Ray, C., Serres, P., Schmitz, T., Cabrol, D., & Goffinet, F. (2007). Manual rotation in occiput posterior or transverse positions: risk factors and consequences on the cesarean delivery rate. Obstetrics & Gynecology110(4), 873-879.

Lieberman, E., Davidson, K., Lee-Parritz, A., & Shearer, E. (2005). Changes in fetal position during labor and their association with epidural analgesia.Obstetrics & Gynecology105(5, Part 1), 974-982.

Reichman, O., Gdansky, E., Latinsky, B., Labi, S., & Samueloff, A. (2008). Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section. European Journal of Obstetrics & Gynecology and Reproductive Biology136(1), 25-28.

Shaffer, B. L., Cheng, Y. W., Vargas, J. E., & Caughey, A. B. (2011). Manual rotation to reduce caesarean delivery in persistent occiput posterior or transverse position. Journal of Maternal-Fetal and Neonatal Medicine24(1), 65-72.

Simkin, P. (2010). The fetal occiput posterior position: state of the science and a new perspective. Birth37(1), 61-71.

Stremler, R., Hodnett, E., Petryshen, P., Stevens, B., Weston, J., & Willan, A. R. (2005). Randomized Controlled Trial of Hands‐and‐Knees Positioning for Occipitoposterior Position in Labor. Birth32(4), 243-251.

Recommended resource: The fetal occiput posterior position: state of the science and a new perspective http://www.ncbi.nlm.nih.gov/pubmed?term=simkin%202010%20posterior by Penny Simkin.


 

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LaborPro: Third Generation of Monitoring Technology Promising to Improve Outcomes, Without Adequate Testing or Proven Benefit

September 23rd, 2011 by avatar

New technology claims to be a ‘breakthrough in non-invasive labor progress monitoring,’ using ultrasound and GPS-like imaging to determine pelvic diameter, cervical dilation, and the position and descent of the baby.  LaborPro claims that their advanced technology can reduce inaccuracies inherent in manual assessment of cervical dilation and fetal head station and position, and that the use of their technology will lead to fewer unnecessary cesarean sections.  Sounds great…doesn’t it?

When I heard about this technology, I got a sinking feeling. Our grandmothers had X-rays to determine pelvic diameter. Oops, that can damage the baby. Our mothers were introduced to continuous electronic fetal monitoring to make sure that babies were coping well. Oops, that has led to an increase in cesareans without improving outcomes for babies.  And now, we could be the generation that uses ultrasound and GPS to create 3D images of what is happening during labour, leading to…oops….?

LaborPro—the name sounds reassuring and promising, as if the machine has been through birth many times, like an experienced midwife. What the technology offers is so tempting…maybe clinicians would make fewer subjective decisions about labour dystocia (failure to progress) if they could SEE the baby’s head descending. Maybe they wouldn’t inaccurately assess ‘your pelvis is too small,’ if they could measure the pelvis.  And yet…

Pelvic Measurements

•    Pelvic measurements taken while lying down are different than if a woman is upright and moving. When a woman is on hands and knees her pelvic outlet is 0.5 cm bigger than when she is lying down, and movement also helps increase pelvic space. This can make a big difference to the ability of the baby to rotate and descend. Also, while measurements can be made to determine the space between the pelvic bones, the pelvis stretches during labour, and no one can predict how much it will stretch. Pelvic movement is one of the reasons labour hurts.

Optimal Positions and Movement During Labour

•    It seems (from the LaborPro video, the way that sensors are placed, and the way ultrasound is used) that women will need to be supine or semi reclining to have LaborPro applied to them.  This is the least effective position to labour in.

•     It seems that during the use of the LaborPro tool, women must be stationary, as they will have sensors attached to their body.  This is the least effective mode to labour in: it is more effective for women to move around freely during labour to encourage descent and optimal positioning of the fetus.

Ultrasound Safety & Accuracy

•    The use of routine ultrasound during pregnancy continues to be a controversial issue, especially in healthy term pregnancies.  The threshold of safe ultrasound exposure has not been established, nor has it been recently studied in an independent or academic manner. The Society of Obstetricians and Gynaecologists of Canada (SOGC), Health Canada, U.S. Federal Drug Administration, and American Institute of Ultrasound in Medicine (AIUM) all advise against the non-medical use of ultrasound, referring to concerns about tissue overheating and cavitation.

•    Particularly, an extended or repeated exposure of ultrasound to the head of an infant, which houses the brain, has not been extensively studied with regards to safety for the unborn baby.  The LaborPro is applied close to the unborn baby’s head during labour.

•    Ultrasonography measurements with regards to fetal size are notoriously inaccurate.  What makes the ultrasound machine suddenly an extremely accurate measurement of size and position?

•    What happens if the sensors slip or move during the use of LaborPro? Will this create inaccurate results, leading to unnecessary interventions?

Non-Invasive?

•    While LaborPro claims its technology is non-invasive, to determine cervical dilation, the technology still requires that clinicians insert a finger into the woman’s vagina. The difference with LaborPro is that a positioning sensor is attached to the clinician’s finger, so the technology can determine how dilated the woman is, rather than the clinician. This means women will continue to have vaginal exams and the use of technology, doubling up on the quantifying, measuring, left brained, logical, medical assessment without evidence of health benefits.

•    Labour is largely a function of the parasympathetic nervous system, particularly the dilatation phase.  Any disturbance, interference in a woman’s privacy, interruptions, or breakdown in her confidence in her ability to give birth will introduce fear into the equation.  Fear counters parasympathetic functions, and slows down labour progression.  LaborPro has the potential to disturb a woman’s concentration and the quiet peacefulness of a birth environment, interfere with her privacy by techs, physicians, or other staff entering and exiting her room more often than before or in a more disturbing manner because of the moving of equipment, and the potential to break down a woman’s confidence because of the implication that technology is a more trustworthy entity than the woman’s body or low tech approach by care providers.  Research shows the benefits of having a low tech approach encourage favourable outcomes.

Loss of Hands-on Skills and Human Touch

•    The LaborPro tool has the potential to undermine care provider hands on skills.  Research (referenced and expanded upon in Atul Gawande’s book “Better”) shows that a low tech approach costs health care systems less and results in better health for patients, regardless of which area of medicine is assessed.

•    In times of emergency (i.e. electrical blackout, fire), natural disaster (earthquake, flood etc.), and widespread lack of access to technology because of a rural environment, hands on skills are imperative. Surges in patient loads can lead to all machines or surgical suites being in use, along with a lack of technicians or physicians trained in using the technology.

•    All medical practitioners recognize the importance of good hands on skills and human touch in medicine.  Despite this, we so often look  to technology to tell us what we can determine clinically.  The use of a pulse oximeter is a great example: a patient’s pulse may be determined by palpating the radial artery and her blood oxygen concentration can be estimated by assessing her skin colour.  The oximeter is sometimes wrong, and a quick assessment is more accurate.  Good manual measurement skills will be lost if technology usurps hands on assessment via LaborPro.

•    Yes, the accuracy of measuring actual centimetres dilated varies between care providers and is subjective.  But knowing the exact number is not as important as assessing progress: is a woman more or less dilated than the last time I measured? And assessing the presence of remaining cervix: is the cervix fully dilated or not?  Exact centimetre accuracy is less important.

Add to all these concerns the fact that NONE of the clinical trials (which were most likely funded by Trig Medical, the company selling LaborPro) showed that the technology was any better than digital examination for determining dilatation, position, and station. The research sample sizes were small, and did not include any outcome data—which means it certainly does not support or even address the claim that LaborPro will reduce caesarean sections, and there is no data on whether the health of mothers and babies are improved with the technology.

One of the selling features of LaborPro is that it automatically stores data on labour—which could then be used to defend medical personnel in malpractice suits. In fact, some have suggested that this may in fact be one of the main reasons hospitals will buy this equipment.

TrigMed is on a circuit in the US, at conventions such as ACOG 2011, Birth 2011, ISUOG 2011, and RSNA 2011. They are presenting their product to obstetricians, promising results that have no academic research behind them.

I have a better idea. Instead of implementing an expensive, untried product, which will most likely lead to more problems and misdiagnoses, let us move towards a proven approach to labour and delivery: supportive one-to-one care, allowing labour to begin on its own, and patience with the birth process.   Let mothers learn to listen to their own bodies and babies, and let mothers be the ones to tell medical personnel what is happening within themselves. Let us allow nature to unfold in the way it is designed, slipping babies into the world with as little interference as possible.

 

Guest Posted by: By Melissa Vose and Asheya Hennessey, Directors, Mothers of Change for Maternity Care 

 


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