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 & Gynecology, 121(6), 1158-1160.

Goldenberg, R. L., Cliver, S. P., Bronstein, J., Cutter, G. R., Andrews, W. W., & Mennemeyer, S. T. (1994). Bed rest in pregnancy. Obstetrics & 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 cervix. Obstetrics & Gynecology, 121(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 Data. Obstetrics & Gynecology,121(6), 1305-1308.

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