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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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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.

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The Wax Home Birth Meta-Analysis: An Outsider’s Critique

October 23rd, 2012 by avatar

Today’s post is a fascinating interview that took place between Rebecca Dekker, PhD, RN, APRN of Evidence Based Birth and Kyoung Suk Lee, PhD, MPH, RN, APRN. Rebecca asked Dr. Lee to provide a review of the Wax Home Birth Meta-Analysis, as an “unbiased outsider”, but highly skilled researcher.  Dr. Lee’s comments and critique are fascinating and provided me with many further thoughts.  Please enjoy Rebecca’s interview and share your comments. – SM

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http://www.flickr.com/photos/eyeliam/7353095052/

Shortly after starting my website, www.evidencebasedbirth.com, I had several people ask me if I could write an article about the research evidence on home birth. However, I was hesitant to do so for several reasons. Mainly, I was worried that I could not look at the evidence in an objective manner. My husband and I had recently chosen a home birth for our second child. I was worried that it would be difficult to objectively examine the research evidence on home birth, given my personal experience. The blogosphere is full of people who are strongly pro-home birth or anti-home birth, and their evaluations of the evidence are usually written through the lens of their own biases. I didn’t want to add to the plethora of biased articles already out there.

Then I had a sudden burst of inspiration. What if I asked one of my colleagues—who has no biases about childbirth—to review the home birth literature for me? In particular, I wanted to find someone who could review the Wax home birth meta-analysis (Wax, Lucas et al. 2010) and give me a fair assessment of its scientific value.

I chose the Wax meta-analysis for this review because in 2011, the American Congress of Obstetricians and Gynecologists emphasized the results of the Wax study in its official statement on home birth. Their statement said: “Women inquiring about planned home birth should be informed of its risks and benefits based on recent evidence. Specifically, they should be informed that although the absolute risk may be low, planned home birth is associated with a twofold to threefold increased risk of neonatal death when compared with planned hospital birth.”(ACOG, 2011)

Dr. Kyoung Suk Lee, PhD, MPH, RN, APRN

It did not take me long to figure out who I would ask to review the Wax study. Dr. Kyoung Suk Lee is considered by her colleagues to be a rising star in the field of cardiovascular research. She recently graduated with a PhD in Nursing, and she just accepted a job at a research university. People who work with Dr. Lee say that she is extremely intelligent, hard-working, and a future leader in her field. Dr. Lee’s expertise has been recognized with research awards from the Heart Failure Society of America, the Society for Heart-Brain Medicine, and the Cleveland Clinic Heart-Brain Institute, among others. She has published her work in nursing and cardiology journals. Furthermore, I knew that Dr. Lee did not have any biases about childbirth, home birth, or hospital birth. I asked Dr. Lee if she would be willing to review the Wax meta-analysis for me, and she kindly agreed.

What follows is my interview of her about the study and its results (RD in bold, KSL unbolded).

Do you have any biases or conflicts of interest related to home or hospital birth?

I do not have any biases related to home or hospital birth.

Could you summarize the methods and results of the Wax study?

The purpose of this meta-analysis was to compare maternal and neonatal outcomes between planned home-and hospital-births.

Using an electronic database search and bibliography search, the authors retrieved 237 articles and included 12 articles in their meta-analyses. Of 12 articles included, 3 were conducted after 2000 while 9 were conducted before 2000. Of 12 articles, 2 were conducted in the US (one was a retrospective design) while 10 were conducted outside US.

Women in the planned home birth group had better maternal outcomes than women in the planned hospital group. They had fewer interventions such as epidurals and episiotomies, and lower morbidity (infection, 3rd or 4th degree lacerations, hemorrhages, and retained placenta). There were no differences in cord prolapse between the two groups.

For neonatal outcomes, babies born to women in the planned home birth group were less likely to experience prematurity and low birth weight. However, babies born to women in the planned home birth group were more likely to experience neonatal death compared to women in hospital birth.

What is the difference between neonatal and perinatal mortality? What does this have to do with the results?

Based on the definitions given by the authors, neonatal mortality was defined as “death of live born child within 28 days of birth.” This is a subset of an overall outcome– perinatal mortality, which was defined as “stillbirth (of at least 20 weeks or 500g) or death of live born child within 28 days of birth.”

According to the authors, there were no differences in perinatal death (the overall outcome) between planned home birth and hospital birth groups. However, homebirth was associated with 2 times higher risk for neonatal death (the subset of deaths occurring 28 days after birth) in all infants and 3 times higher risk for neonatal death in infants who did not have any congenital birth defects.

Interestingly, if you look at page 243.e3, the authors did a sensitivity analysis. In this analysis, they excluded the studies that had home births that were not attended by certified midwives or certified nurse midwives. In this analysis, they found that there were no differences in neonatal deaths between the home birth and hospital birth groups. This means that in the studies in which midwives with certification of some kind attended home births, the outcomes were the same except there was no increase in the neonatal death rate. In my opinion, we have to pay attention to results of sensitivity analyses because this allows us to see the results based on studies which were definitely known to be eligible or clearly described their methods and outcomes.

What is your opinion on the scientific rigor of this meta-analysis?

One thing that was strange to me is the odds ratios (ORs) in the tables. For example, in table 2, under morbidity, the percentages of infection between home births and hospital births were 0.7 vs. 2.6 (its OR was 0.27) while percentages of perineal laceration were 42.7 vs. 37.1 (its OR was 0.66). To a researcher, these numbers don’t make sense.

Many of the studies included were older (half of the studies were conducted more than 20 years ago) so results may not reflect the current practice at home births or hospital births.

The authors did not provide detailed information on how they evaluated the quality of studies included, although they cited a paper describing the method of study evaluation. This makes it difficult if not impossible to determine whether the studies they included were of good or poor quality.

The authors mentioned that women with high risks would prefer hospital births so that it would expect that home births have better outcomes than hospital births in some maternal and neonatal outcomes. If this was a concern, I wonder why the authors didn’t just focus on only the studies that used matching methods, in order to minimize confounding factors.

What is the difference between relative risk and absolute risk, and how does that apply to women who want to have a home birth?

Absolute risk is the probability of something occurring. They may be expressed as percentages or ratios. For example, neonatal mortality rate in the United States is 2.01 per 1,000 live births. This is .201 percent (2.01/1000 = .201/100).

http://www.flickr.com/photos/mikeporcenaluk/3789756395/

Relative risk is a comparison between different risk levels, such as the neonatal mortality rate of home birth compared to the neonatal mortality rate of hospital birth. The researchers found that there was a higher relative risk in neonatal mortality at home births compared to hospital births, but the overall absolute risk for both was small.

How can women know whether the Wax study results would be applicable to their own individual situation?

Meta analysis is one way to generalize findings from different studies. However, women and clinicians should interpret these results cautiously because the studies included were very different from one another and some of the studies included may not have been of good quality. Also, it would be important to note that the overall neonatal death rate that they report reflects home births that were attended by midwives as well as those that may not have had any kind of certified midwife present.

Because this study seems to have some flaws, the conclusion is tentative. I do not know if this article has any implications for pregnant women.

What do you think is the value of asking someone with no conflicts of interest to evaluate controversial research? Does Dr. Lee’s even-handed critique make you view the results of this study any differently? How do you feel about Dr Lee’s conclusion that the study’s results are tentative, and that the Wax study might not have any implications for pregnant women? Please share your thoughts and comments with other readers.

References

(2011). “ACOG Committee Opinion No. 476: Planned home birth.” Obstetrics and gynecology 117(2 Pt 1): 425-428.

Wax, J. R., F. L. Lucas, et al. (2010). “Maternal and newborn outcomes in planned home birth vs planned hospital births: a metaanalysis.” Am J Obstet Gynecol 203(3): 243 e241-248.

About Rebecca Dekker

Rebecca Dekker, PhD, RN, APRN, is an Assistant Professor of Nursing at a research-intensive university and author of www.evidencebasedbirth.com. Rebecca’s vision is to promote evidence-based birth practices among consumers and clinicians worldwide. She publishes summaries of birth evidence using a Question and Answer style.

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Journal of Perinatal Education 20.1 Feature Article: Umbilical Cord Blood: Information for Childbirth Educators

April 11th, 2011 by avatar

The Spring 2011 issue of the Journal of Perinatal Education (JPE 20.1) has already landed in your mailbox and is now available on-line. As always, it is chock-full of illuminating and informing articles about perinatal health care issues.  Considering our recent re-post of Dr. Nicholas Fogelson’s Grand Rounds lecture on delayed umbilical cord (UC) cutting and clamping, the continuing education module contained in this issue of the JPE caught my attention: Umbilical Cord Blood: Information for Childbirth Educators by Renece Waller-Wise, MSN, CNS, CLC, CNL, LCCE.

As options for UC collection and banking/donation are increasing, questions about efficacy and indications grow.  Waller-Wise does a tremendous job in her article providing not only the background on stem cell research (dating back to the 1950s) and transplant and collection (1980s and 1990s, respectively) but she reviews the illnesses that are currently amenable to treatment with umbilical cord blood stem cell transplantation along with the advantages and disadvantages of employing this treatment modality.

While the use of umbilical cord blood stem cells to treat previously identified familial illness in a first degree relative provides a primary indication for collection and banking, the procedure and storage is costly, the cells have a definitive shelf life and success of transplant is not necessarily guaranteed (see Waller-Wise’s article for details).  And the chance of using these stem cells for treatment at all?  At best, the likelihood is estimated to be 1 /2,700.[1]

Beyond whether or not cord blood banking is a reasonable “insurance policy” to invest in, another debate is ensuing which heightens the gravity of the following questions: “Should we, or should we not retrieve UC blood at all?  And if so, should the commonly accepted practices surrounding cord blood collection be altered?”

In Dr. Fogelson’s Grand Rounds videos, his message is clear: immediate clamping and cutting of the umbilical cord deprives the newborn of nearly 20mL/kg of her potential blood volume.  As Fogelson describes it, “…by clamping the umbilical cord [early] you phlebotomize the baby of 40% of its blood volume.”  Dr. Fogelson goes on to explain the various suspected and documented morbidities associated with newborns who have been deprived of this extra (read: nature-intended) blood volume.

Renowned family practice and obstetrics physician, Dr. Sarah Buckley, echoes these concerns in her seminal book, Gentle Birth, Gentle Mothering:  A Doctor’s Guide to Natural Childbirth and Gentle Early Parenting Choices. Dr. Buckley expands upon the risks of early umbilical cord cutting and clamping this way:

“Active management [of the Third Stage] also creates specific difficulties for mother and baby. In particular, active management can lead to the deprivation of one third,
on average, of a newborn’s expected blood volume. When active
management is used, this extra blood, intended to perfuse the newly
functioning lungs and other vital organs, is discarded along with the placenta.
Possible consequences include breathing difficulties and anemia,
especially in vulnerable babies; long-term effects on brain development
are also very plausible.”[2]

 

But how much of this placental blood is the newborn really deprived of during UC blood collection?

Depending on the system used (needle + syringe extraction vs. needle + dependent bag collection) along with provider skill/preference, cord blood collection requires between 40-200mL of blood such that an adequate volume of stem cells might be retrieved, processed, and made available for transplant.  This volume, incidentally, is on par with the amount of blood a newborn can receive via placental transfusion when the cord is left patent for at least three minutes after birth.  (See Dr. Buckley’s and Dr. Fogelson’s works, referenced above.)  Because of this, common practice is to immediately clamp the umbilical cord following the baby’s birth and initiate cord blood collection moments later—capturing every drop of blood possible into the collection device.

The question, then, becomes:  does the benefit of potentially successful treatment of current familial illness, or future autologous UC blood stem cell transplantation, outweigh the risk of significant newborn phlebotomization?

Before jumping into this debate, my heart tells me there is a third option.

Google “cord blood withdrawal without clamping” and you will find message board and blog site discussions like this one where anecdotal evidence is beginning to emerge and become the subject of hot debate:  it just might be possible to delay clamping & cutting the umbilical cord and collect a cord blood sample that satisfies requirements for banking/transplantation purposes. Make no mistake:  I am not presenting these discussions as science, evidence or infallible support for creating a new Third Stage practice.  I am simply relaying what some maternity care providers have begun doing on their own.  (Isn’t that how medical advances have developed in the past?  Someone tries something new and, low and behold it works…leading to the adoption of the new practice by others?)

The catch, of course, if how much UC blood can be collected after delayed clamping, and whether collection can take place before clotting sets in within the cord/placenta.  One maternity care provider respondent on the Mothering.com message board offered a depiction of how she goes about collecting cord blood after placental delivery:

“The bag is about 500mL, I can usually get about 1/3 of a bag, so a bit more than 150mL, even after the placenta is born.  I usually put the placenta on a counter top, with the bag resting on the floor, start low by the clamp and move up the cord, and use all those juicy veins on the fetal side of the placenta. If you elevate the placenta with the cord hanging, quite a bit will flow into the cord. Obviously, you’re not going to get a full 500mL if you wait for the birth of the placenta, but you can get a decent amount with a little patience and multiple sticks. And you don’t want to wait too long after the birth of the placenta, or the blood coagulates, so someone else should be watching mama and baby while the other does the collection.”

 

If the practice described above is truly reproducible, it would suggest that there is plenty of cord blood available (and perhaps more than what has been previously assessed).

In 2007, the American Academy of Pediatrics released a statement providing the following guidance as a part of its endorsement of cord blood banking when known familial illnesses treatable by stem cell transplant exist:

“The cord blood stem cell-collection program should not alter routine practice for the timing of umbilical cord clamping.”[3]

 

ACOG’s Committee Opinion paper #399 (Feb ’08), Umbilical Cord Blood Banking offers the same guidance. [1]

If we can all agree that in most cases, delaying the clamping and cutting of the umbilical cord constitutes the best, evidence-based practice, then the above AAP statement ought to apply to cord blood collection after a sufficient amount of time has transpired for placental transfusion to take place.

If you look on the website* of one of the largest cord blood banking companies, you can watch a demonstration of umbilical cord blood collection—complete with instructions on how to collect an adequate volume after the birth of the placenta:

The AAP along with ACOG now advise maternity care providers to counsel interested patients on the risks and benefits of cord blood banking.  Factors such as the likelihood of actually using the stem cells, philanthropic drive to donate stem cells to public cord blood banks and the cost of collection and storage should all be taken into consideration when expectant parents are contemplating this choice.  As should the importance of what that added blood volume can do for the newborn whose body is undoubtedly expecting it.  And I, for one, can’t help but to believe a viable third option exists in which the newborn is granted the lion’s share of the placental transfusion while a small and remaining amount is collected for cord blood banking, when the proper indications are present.

Surely a study can be formed to test this hypothesis.

To learn more about umbilical cord blood collection and storage, go here to read Waller-Wise’s full article (compliments of the Journal of Perinatal Education and Springer Publishing) and don’t forget to take the post test to earn continuing education credits!


[1]Umbilical cord blood banking. ACOG Committee Opinion No. 399.  American College of Obstetrics and Gynecologists. Obstet Gynecol 2008;111:475-7

[2] Gentle Birth, Gentle Mothering : A Doctor’s Guide to Natural Childbirth and Gentle Early Parenting Choices by Sarah J Buckley MD (Celestial Arts, Berkeley CA,2009) p 156; www.sarahbuckley.com

[3] http://aappolicy.aappublications.org/cgi/content/full/pediatrics;119/1/165; Recommendations #7

*Neither Lamaze International nor the editor or contributing writers to Science & Sensibility endorse any particular cord blood bank or registry organization or company.

Posted by:  Kimmelin Hull, PA, LCCE

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