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Bed Rest to Prevent Preterm Birth Both Ineffective and Harmful

July 9th, 2013 by avatar

 Today, regular contributor, Henci Goer takes a look at the recent study on prescribing bed rest for the prevention of preterm birth.  Despite not preventing a premature baby, and even possibly increasing the likelihood, it is still routinely recommended for pregnant women.  Please enjoy this research review and share your thoughts with Henci and I in the comments section. – Sharon Muza, Science & Sensibility Community Manager.

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© Sindea Horste sindea.org

In May, The New York Times and Reuters ran articles on a study published the following month finding that restricting activity did not prevent preterm birth in first-time moms with a short cervix (less than 30 mm) (Grobman 2013). A secondary analysis of a randomized controlled trial of injected progesterone vs. placebo, investigators looked at the effect of “activity restriction,” defined as restriction from sexual activity, work, or nonwork activity, in 646 women. They found that 39% of women reported being restricted in one or more of these categories, and two-thirds of them (68%) were restricted in all three with the vast majority (25th to 75th percentile) receiving that prescription between 24 and 28 weeks gestation. Birth before 37 weeks was three times (odds ratio: 2.9) more likely in the restricted group (raw difference: 37% vs. 17%). Adjustment for trial assignment group and factors associated with likelihood of being placed on activity restriction, didn’t much change that ratio (odds ratio: 2.4). The same held true for the likelihood of birth before 34 weeks (odds ratio: 2.3). And here’s the kicker: not mentioned in the secondary analysis is that the trial itself found that progesterone treatment made no difference in preterm birth rate at less than 37 weeks (25% vs. 24%) (Grobman 2012 ).

In other words, not prescribing activity restriction was effective; progesterone treatment was not. Study authors speculated that the reason for the paradoxical effect of activity restriction may be that it is stressful and anxiety provoking and that anxiety and stress may increase risk of adverse pregnancy outcomes.

The uselessness of bed rest is hardly “stop the presses” news. We have known that bed rest was ineffective at least since 1994 when a review reported that this particular emperor had no clothes (Goldenberg 1994). Studies since have reinforced that conclusion. An accompanying commentary in the same issue as Grobman et al’s study reports on the findings of Cochrane systematic reviews on the effects of bed rest (McCall 2013). Bed rest neither prevents miscarriage, preeclampsia, or preterm birth with singleton or multiple gestation, nor treats hypertension or impaired fetal growth. Publication dates for the set of Cochrane reviews range from 2000 (impaired fetal growth) to 2010 (multiple pregnancy). The review on preterm birth with singleton gestation, the subject of Grobman et al.’s study, was published in 2004.

These consistent results, however, have not affected practice. An editorial on the Grobman and McCall articles states that 95% of obstetricians recommend activity restriction or bed rest and that 71% of maternal-fetal medicine specialists responding to a survey would recommend it after arrested preterm labor despite the finding that 72% of survey participants didn’t think it would help (Biggio 2013). Why aren’t doctors paying attention to their own research? Biggio thinks it may be fear of liability if a bad outcome were to occur and bed rest hadn’t been prescribed and the belief that bed rest is harmless. It isn’t, and this is known too. McCall, Grimes, and Lyerly quote from an American College of Obstetricians and Gynecologists’ Practice Bulletin on managing preterm labor (ACOG 2012):

Although bed rest and hydration have been recommended to women with symptoms of preterm labor to prevent preterm delivery, these measures have not been shown to be effective for the prevention of preterm birth and should not be routinely recommended. Furthermore, the potential harm, including venous thromboembolism, bone demineralization, and deconditioning, and the negative effects such as loss of employment, should not be underestimated. [Emphasis mine.]

To this, McCall, Grimes, and Lyerly add adverse psychosocial effects on women and their families, including the potential for women blaming themselves when bed rest fails to avert preterm birth, and now Grobman et al’s study suggests the possibility of increasing the risk of preterm birth.

In the Reuters article, Grobman states that “any pregnant woman who is told to restrict her activity or stay in bed should discuss with her doctor whether there is data to support that recommendation given her condition.” Fair enough, but how is she supposed to know to do that? What role can or should childbirth educators and doulas play? What might Lamaze International or other childbirth-related organizations do to spread the word? What are your thoughts?

References 

ACOG practice bulletin no. 127: Management of preterm labor. (2012). Obstet Gynecol, 119(6), 1308-1317. doi: 10.1097/AOG.0b013e31825af2f0

Biggio Jr, J. R. (2013). Bed Rest in Pregnancy: Time to Put the Issue to Rest.Obstetrics & Gynecology121(6), 1158-1160.

Goldenberg, R. L., Cliver, S. P., Bronstein, J., Cutter, G. R., Andrews, W. W., & Mennemeyer, S. T. (1994). Bed rest in pregnancyObstetrics & Gynecology,84(1), 131-136.

Grobman, W. A., Gilbert, S. A., Iams, J. D., Spong, C. Y., Saade, G., Mercer, B. M., … & Van Dorsten, J. P. (2013). Activity restriction among women with a short cervixObstetrics & Gynecology121(6), 1181-1186.

Grobman, W. A., Thom, E., Spong, C. Y., Iams, J. D., Saade, G. R., Mercer, B. M., … & Van Dorsten, J. P. (2012). 17 alpha-hydroxyprogesterone caproate to prevent prematurity in nulliparas with cervical length less than 30 mm.American journal of obstetrics and gynecology.

McCall, C. A., Grimes, D. A., & Lyerly, A. D. (2013). “Therapeutic” Bed Rest in Pregnancy: Unethical and Unsupported by DataObstetrics & Gynecology,121(6), 1305-1308.

ACOG, Bed Rest, Childbirth Education, Evidence Based Medicine, Guest Posts, Maternal Quality Improvement, Maternity Care, Medical Interventions, New Research, Pre-term Birth, Research , , , , , , , ,

Whether Women Have Cesareans Is Mostly Arbitrary

March 21st, 2013 by avatar

 Regular contributor Henci Goer, author of several books including Optimal Care in Childbirth as well as the expert on Lamaze International’s “Ask Henci” site, takes a look at a recent study that examines the wide divergence in cesarean rates amongst U.S. hospitals.  Read Henci’s take and see what she concludes might be behind this rate variability. – Sharon Muza, Community Manager, Science & Sensibility

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© Patti Ramos Photography

If any doubt remained that the likelihood of cesarean depends mostly on care provider philosophy and practices, a study of variation in cesarean rates in U.S. hospitals has laid it to rest. Investigators plotted cesarean surgery rates during 2009 by their percentile at 593 U.S. hospitals with at least 100 deliveries, comprising 817,318 women in all (Kozhimanni 2013). Rates ranged from 7% to 70%, a 10-fold variation.

Thinking that hospital factors might explain some of the variation, the investigators compared rates according to hospital size, whether the hospital was a teaching hospital, and whether it was rural. None had any effect. Average cesarean rates were similar to the overall average rate regardless of hospital characteristics.

Variation in population characteristics likewise could explain variation in cesarean rates. Accordingly, investigators looked at a more homogeneous low-risk subset of women who were at term (37 weeks or more), carrying one head-down baby, and who had no prior cesareans. This, they reasoned, should reduce the variation in rates. Wrong again. The range widened. Rates among low-risk women ranged from a little over 2% to nearly 37%, a 15-fold variation instead of a 10-fold one.

The investigators stopped with expressing concern over the large variation in cesarean rates, writing: “There is an urgent need to address maternity care quality in general and rising cesarean rates and variation in practice patterns in particular” (p. 531), but their data tell us something more: few hospitals had anything close to reasonable rates.

The mean cesarean rate among women overall was 33%. The World Health Organization holds that cesarean rates should not exceed 15% because research shows that as cesarean rates rise above this threshold, they necessarily are performed in less clear cut situations, and the risks of the surgery begin to outweigh its benefits. Beyond 15%, maternal and neonatal morbidity and mortality rise in parallel with further increase. Only 2 of the 593 hospitals had cesarean rates of 15% or less. Indeed, only 21 hospitals had rates of 20% or less.

In the low-risk population, the mean cesarean rate was 12%. The recent analysis of 18,084 women planning birth center births gives us a fix on whether this is a reasonable rate for low-risk women (Stapleton 2013). Of the 14,881 women admitted in labor to the 79 participating birth centers, 6% delivered by cesarean, and perinatal outcomes were equivalent to those in similar women planning hospital birth. Only 23 of the 593 hospitals had a cesarean rate of 6% or less in their low-risk cohort.

To be fair, the low-risk hospital dataset wasn’t able to identify women with problems that would increase their likelihood of cesarean but who would have been excluded from birth center care. The birth center data, however, provides a handle on the possible effect on cesarean rate. Six percent of women planning birth at the birth center were risked out because of pre-eclampsia, non-reassuring fetal testing, postdates, or prelabor rupture of membranes and no labor. Let us assume that these problems occurred at the same rate in the low-risk hospital population. Let us further assume that all women with these problems ended up with a cesarean, which is highly unlikely. Those assumptions would boost the birth center baseline cesarean rate of 6% by another 6% or to 12% for the low-risk hospital population. Even making this extreme assumption, 271 hospitals, nearly half, had rates greater than 12%.

What’s the take-home? Practitioners with appropriate cesarean rates are thin on the ground. Women need to seek out care providers whose judgment on when a cesarean is indicated can be trusted. (I should add that they are likely to have better luck with a midwife, but it isn’t a sure thing.) Women free of medical or obstetrical risk factors may wish to plan to birth in a free-standing birth center or at home because while individual practitioners’ rates may vary within institutions, a high hospital rate—true of nearly all of them—creates a cesarean–friendly culture.

How would you use this research study when teaching classes or working with clients or patients?  Do you think that women do enough research and investigation when selecting a provider and a birth facility? Please share your thoughts. – SM

References

Kozhimannil, K. B., Law, M. R., & Virnig, B. A. (2013). Cesarean Delivery Rates Vary Tenfold Among US Hospitals; Reducing Variation May Address Quality And Cost Issues. Health Aff (Millwood), 32(3), 527-535. doi: 10.1377/hlthaff.2012.1030 http://www.ncbi.nlm.nih.gov/pubmed/23459732

Stapleton, S. R., Osborne, C., & Illuzzi, J. (2013). Outcomes of care in birth centers: demonstration of a durable model. J Midwifery Womens Health, 58(1), 3-14. doi: 10.1111/jmwh.12003 http://www.ncbi.nlm.nih.gov/pubmed/23363029

 

 

 

 

 

 

Cesarean Birth, Guest Posts, informed Consent, Maternal Quality Improvement, Maternity Care, Medical Interventions, New Research, Push for Your Baby, Research , , , , , ,

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 , , , , , , ,

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.


 

Babies, Cesarean Birth, Epidural Analgesia, Guest Posts, Maternity Care, Medical Interventions, Research , , , , , , , ,

Elective Induction at Term Reduces Perinatal Mortality Without Increasing Operative Delivery? Looking Behind the Curtain

May 29th, 2012 by avatar

A recent study of elective induction at term purports to show that it would reduce perinatal mortality without affecting spontaneous birth rates, although it would increase admission to a special neonatal care unit if done before 41 weeks. The study, conducted in Scotland, analyzed outcomes of 1,271,549 women carrying a singleton, head-down baby of 37 to 40 weeks gestation who gave birth between 1981 and 2007. (Forty-one weeks was considered postterm.) Women with prior cesarean, breech baby, or placenta previa were excluded. Elective induction was defined as induction with no medical indications (hypertensive or kidney disorders, thromboembolic disease, diabetes, liver disorders, pre-existing medical disorder, antenatal investigation of abnormality, suspected fetal abnormality, fetal compromise, or previous stillbirth or neonatal death), and 176,136 women met these criteria. Perinatal mortality was defined as stillbirth or death within the first month, excluding deaths associated with congenital anomalies. Outcomes were adjusted for maternal age, parity (no prior births vs. one or more prior births), time period, and birth weight.

Investigators reported outcomes by week in two ways: women electively induced compared with women not electively induced who delivered after that week and women electively induced compared with women not electively induced who delivered in or after that week. I will report outcomes according to the second method because it is less biased.

Perinatal mortality rates declined from 2.4 per 1000 at 37 weeks to 1.6 per 1000 at 41 weeks in the “not electively induced” population and varied from 0.9 to 0.6 per 1000 in the electively induced population, showing no trend, which meant that the excess

Drewesque, via Flickr, Creative Commons Attribution

perinatal mortality rate fell from 2.3 per 1000 more deaths at 37 weeks in the “not electively induced” population to 0.9 more at 41 weeks. That would seem to clinch the argument for elective term induction were it not for one fatal flaw: investigators did not compare similar populations. They isolated a low-risk—I may even say ultra-low-risk—group of women and compared them with everyone else, including women with the high-risk conditions listed above! Finding lower perinatal mortality rates should not be surprising. It would have been extraordinary if they had not.

Even with that advantage, more babies were admitted to special or intensive care nurseries after elective induction at every week through 40 weeks, which contradicts the current belief that elective delivery at 39 weeks poses no excess risk. Excesses declined from 94 more babies per 1000 with elective induction at 37 weeks to 10 more babies per 1000 at 40 weeks. (At 41 weeks, 3 more babies per 1000 were admitted to special or intensive care in the “not electively induced” population.)

What about finding similar spontaneous vaginal birth rates? Spontaneous birth rates were, indeed, similar between groups, but more women delivered via cesarean surgery in the electively induced group. Depending on the week, 0.3 to 1.5 more women per 100 electively induced had cesareans. Spontaneous birth rates were similar because the cesarean excess was offset by an excess of instrumental vaginal deliveries at each week in the “no elective induction” group. An excess of instrumental deliveries is concerning primarily because of the increased likelihood of anal sphincter injury; however, an excess in cesarean deliveries is far more serious, carrying as it does increased likelihood of severe maternal and perinatal morbidity and mortality in both current and future pregnancies.

Rob, Joyce, Alex & Nova's photostream, via Flickr, Creative Commons Attribution

Rob, Joyce, Alex & Nova's photostream, via Flickr, Creative Commons Attribution

Furthermore, the investigators chose not to report cesarean rates according to parity. Women with a prior vaginal birth or births will be little affected by induction, but first-time mothers are a different story. Studies (see references below) comparing term elective induction with spontaneous onset report that elective induction roughly doubles the chance of cesarean with excesses ranging from 3 to 31 more women per 100 having labor end in cesarean. Three studies (Hannah et al. 1996, Kassab et al, 2011; Pavicic et al. 2009.) specifically evaluating elective induction at 41 weeks compared with expectant management for at least one more week in low-risk first-time mothers report a remarkably similar excess: 8 to 9 more cesareans per 100 women induced electively. In first-time mothers, then, the excess cesarean surgery rate was almost certainly much greater than the excess rate in the Scottish population overall.

So there you have it. Does elective induction at term save babies? We don’t know because the investigators compared apples to oranges. It certainly increases likelihood of admittance to special or intensive neonatal care through 40 weeks, an excess all the more ominous because comparison women were not all low risk. It’s also a safe bet that it substantially increases cesarean surgery rates in first-time mothers going by what other studies have found. And, again, the excess would likely have been greater even in the population overall had investigators compared low-risk women to low-risk women. Lesson learned: if you don’t look at what’s behind the curtain, you may get very misleading ideas of what is really going on.

Boulvain, M., Marcoux, S., Bureau, M., Fortier, M., & Fraser, W. (2001). Risks of induction of labour in uncomplicated term pregnancies Paediatr Perinat Epidemiol, 15(2), 131-138.

Cammu, H., Martens, G., Ruyssinck, G., & Amy, J. J. (2002). Outcome after elective labor induction in nulliparous women: A matched cohort study. Am J Obstet Gynecol, 186(2), 240-244.

Dublin, S., Lydon-Rochelle, M., Kaplan, R. C., Watts, D. H., & Critchlow, C. W. (2000). Maternal and neonatal outcomes after induction of labor without an identified indication. Am J Obstet Gynecol, 183(4), 986-994.

Ehrenthal, D. B., Jiang, X., & Strobino, D. M. (2010). Labor induction and the risk of a cesarean delivery among nulliparous women at term. Obstet Gynecol, 116(1), 35-42.

Glantz, J. C. (2005). Elective induction vs. Spontaneous labor associations and outcomes. J Reprod Med, 50(4), 235-240.

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.

Luthy, D. A., Malmgren, J. A., & Zingheim, R. W. (2004). Cesarean delivery after elective induction in nulliparous women: The physician effect. Am J Obstet Gynecol, 191(5), 1511-1515.

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.

Maslow, A. S., & Sweeny, A. L. (2000). Elective induction of labor as a risk factor for cesarean delivery among low-risk women at term. Obstet Gynecol, 95(6 Pt 1), 917-922.

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.

Seyb, S. T., Berka, R. J., Socol, M. L., & Dooley, S. L. (1999). Risk of cesarean delivery with elective induction of labor at term in nulliparous women. Obstet Gynecol, 94(4), 600-607.

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.

van Gemund, N., Hardeman, A., Scherjon, S. A., & Kanhai, H. H. (2003). Intervention rates after elective induction of labor compared to labor with a spontaneous onset. A matched cohort study. Gynecol Obstet Invest, 56(3), 133-138.

Vardo, J. H., Thornburg, L. L., & Glantz, J. C. (2011). Maternal and neonatal morbidity among nulliparous women undergoing elective induction of labor. J Reprod Med, 56(1-2), 25-30.

Vrouenraets, F. P., Roumen, F. J., Dehing, C. J., van den Akker, E. S., Aarts, M. J., & Scheve, E. J. (2005). Bishop score and risk of cesarean delivery after induction of labor in nulliparous women. Obstet Gynecol, 105(4), 690-697.

Yeast, J. D., Jones, A., & Poskin, M. (1999). Induction of labor and the relationship to cesarean delivery: A review of 7001 consecutive inductions Am J Obstet Gynecol, 180(3 Pt 1), 628-633.

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