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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas.
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ABSTRACT |
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 ABSTRACT MATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Methods: All women with a singleton gestation and a diagnosis of arrested preterm labor with intact membranes between 24 and 33 weeks, 4 days of gestation were randomly assigned to home or hospital management. Upon completion of a dexamethasone course, women assigned to outpatient management were promptly discharged, and women in the inpatient group were advised to continue hospitalization until 34 weeks. Decreased activity was encouraged in both groups. Bed rest was not strictly enforced. The primary outcome was delivery at 36 weeks or greater.
Results: A total of 101 women of a planned 188 were enrolled at the time of an interim analysis. There was no difference in the primary study outcome between the 2 groups and the trial was terminated. Among the hospitalized women, 71% reached 36 weeks or greater, compared with 72% of those discharged home (P = .89). The mean cervical dilatation in hospitalized women was 2.7 ± 0.5 cm, compared with 2.6 ± 0.5 cm in women discharged home (P = .16). The overall length of hospital stay for the women allocated to hospitalization was 16 ± 13 days.
Conclusion: Compared with hospitalization, outpatient management of women with arrested preterm labor and intact membranes had no effect on the rate of preterm birth.
Level of Evidence: I
For more than 30 years, the standard of practice at our hospital has been to admit women with threatened preterm delivery for the purpose of supervised decreased physical activity in an effort to prolong pregnancy. Given the paucity of data supporting the efficacy of such hospitalization, we embarked on a randomized trial of recommended decreased physical activity in the hospital versus in the patient’s home environment.
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MATERIALS AND METHODS |
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ABSTRACTMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Management of women admitted to the Parkland Labor and Delivery Unit for preterm labor is standardized and consists of intravenous hydration with 5% dextrose in lactated Ringer solution, sedation with intravenous meperidine, and group B streptococcal prophylaxis with ampicillin 2 g intravenously every 6 hours until it is apparent that cervical dilation is not progressive and the patient can be transferred to the Antepartum High-Risk Unit. Meperidine was given in 50–75 mg boluses every 3–4 hours as needed for painful uterine contractions. A single course of dexamethasone, 5 mg intramuscularly every 12 hours for a total of 4 doses, was given for fetal lung maturation. No repeat courses were given. Tocolytic drugs were not used at any time during the trial. Sonography was performed to assess gestational age and rule out multiple gestation, placenta previa, and fetal malformations. The estimate of gestational age was based on the date of the last menstrual period and the results of obstetric ultrasonography, performed during the pregnancy. The reported time of the last menstrual period was accepted as correct if the fundal height, measured between 18 and 30 weeks of gestation, correlated with the week of gestation to within 2 cm. Subjects with discrepancies between the 2 values underwent obstetric ultrasonography. The validity of this approach has been previously described.3
Upon completion of the dexamethasone course, eligible women were approached for randomization by the principal investigator (N.P.Y.). Women were assigned to either home or hospital management by means of a computer-generated random number table, with group allocation masked by placement in consecutively numbered and sealed opaque envelopes. All consenting women were educated about the signs and symptoms of recurrent preterm labor. Women randomly allocated to outpatient management were promptly discharged. Outpatient management for arrested preterm labor consisted of instructing the women to remain at home and stay in bed as much as possible. Women were advised that they could ambulate to the bathroom and living area and shower. They were instructed to avoid standing as much as possible and, in effect, encouraged to become "couch potatoes." The women were advised to avoid sexual intercourse.
Appointments were made for these women to the Parkland Hospital Preterm Birth Clinic where compliance with decreased activity and abstinence from sexual activity were re-emphasized on a weekly basis. Women in the outpatient group who complained of contractions were instructed to return to the hospital to be evaluated for possible recurrent preterm labor. Those whose cervical dilatation remained less than 4 cm continued to be managed as outpatients.
Women in the inpatient group remained in the Antepartum High-Risk Unit and were given instructions similar to those of the outpatient group. Bed rest was not strictly enforced. These women were allowed ad libitum ambulation to the bathroom, shower, and trips to the day room. The women in the inpatient group were advised to continue hospitalization until 34 0/7 weeks of gestation, at which time they were discharged home to follow up in the Preterm Birth Clinic.
The primary outcome selected for this study was delivery at 36 weeks or greater. In a previous investigation at our institution comparing the efficacy of magnesium sulfate infusion with placebo for the prevention of preterm birth in women similar to those enrolled in the present study, 67% of the hospitalized study participants delivered at or beyond 36 weeks.4 We calculated that a total sample size of 188 women would permit detection of a relative decrease of 30% in delivery at or beyond 36 weeks in those women discharged home. Therefore, the study was designed with the expectation that outpatient therapy would lower the proportion of women reaching 36 weeks or more. This sample size provided a power of 80% for a 2-sided test, with a significance of error rate .05. Statistical analyses included 
2, Student t test, and Wilcoxon rank-sum test. P values less than .05 were considered significant. Analysis was performed using SAS 9.1 (SAS Institute Inc, Cary, NC).
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RESULTS |
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Data on the primary outcome (ie, delivery at 36 weeks or greater) were available in 101 women (Fig. 1). Study results were analyzed on an intent-to-treat basis, using the 51 hospitalized women with primary outcome follow-up compared with the 50 women discharged home. The demographic characteristics of the women in these 2 study groups were similar (Table 1). The incidence of prior low birth weight was similar in the 2 study groups (39% versus 34%, P = .59, hospitalized versus discharged home, respectively). The duration of hospitalization before randomization was 2.9 ± 1.8 days in women subsequently randomly assigned to hospitalization, compared with 3.6 ± 2.6 days in women discharged home (P = .11).
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The mean gestational age at randomization was 30.6 ± 2.3 weeks in hospitalized women, compared with 30.8 ± 2 weeks (P = .65) in women discharged home. The mean cervical dilatation in hospitalized women was 2.7 ± 0.5 cm, compared with 2.6 ± 0.5 cm in women discharged home (P = .16). Similarly, there were no significant differences in cervical effacement (55 ± 18% versus 54 ± 17%, P = .59, hospitalized versus discharged home, respectively). The overall length of hospital stay for the women randomly assigned to hospitalization was 16 ± 13 days. Fifteen (29%) of the women in the hospital group left against medical advice after an average of 10 days in the hospital. Another 7 (14%) women randomly allocated to hospitalization delivered before 34 weeks while inpatients. There were no readmissions in the discharged home group except for delivery.
Shown in Table 2 is the duration of pregnancy in women randomly assigned to hospitalization, compared with those discharged home. The incidence of the primary study outcome did not differ significantly between the 2 study groups. Specifically, 71% of hospitalized women reached 36 weeks or greater, compared with 72% of women discharged home, P = .89. There were no significant differences in pregnancy prolongation, measured in days, between the 2 groups. Shown in Table 3 are selected neonatal outcomes in relation to maternal group assignment. There were no significant differences except for respiratory distress syndrome, which occurred more frequently in the hospitalized group. There was one stillbirth during the trial, and this occurred in a woman in the discharged home group. This patient was randomized at 31 weeks, and the fetal death occurred at 32 weeks. The infant weighed 2,005 g and was delivered with no apparent cause of death identified at autopsy.
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The pregnancy outcomes of the 15 women who left against medical advice were compared with those women who remained hospitalized as randomized as well as those women discharged home. There were no significant differences in prolongation of pregnancy or neonatal morbidity between these groups.
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DISCUSSION |
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We terminated this study before its planned completion for several reasons. An interim analysis after 6 years of study revealed virtually no differences between the study groups. In our view, and given our prevailing rate of patient recruitment, we faced the prospect of continuing the trial for 4–5 additional years with no apparent trend suggesting a possible benefit for routine hospitalization. A post hoc power analysis to determine the effect size that has been excluded was performed. The sample size at study termination (ie, 101 women) provides a 60% power of detecting a 30% relative reduction in delivery at 36 weeks or more in the women managed as outpatients. Clearly, our sample size did not reach the conventional 80% power. Consider that delivery at 36 weeks or more occurred in 71% of the hospitalized women and in 72% of those randomized to decreased activity at home. If we were to continue accrual to the proposed 188 subjects (total of 94 in each arm) and the rate of delivery at 36 weeks or more remained constant in the hospitalized arm (71%), to a total of 67 of 94 (71%), then to achieve statistical significance, the rate in those discharged home would have to drop to 41% or lower in the subsequent 44 patients accrued. Thus, the recruitment of 44 more women to each arm would require an extreme imbalance in the rate of the primary outcome to find a statistical significance given the power assumptions we made at the study’s outset. We believe that we can reasonably conclude that the study can be terminated because it is not feasible to overturn the current balance (ie, 71% versus 72%). Moreover, approximately one third of the women recruited to this trial had prior preterm births and are now potential candidates for 17 
-hydroxyprogesterone caproate therapy,5 which could confound interpretation of our results. Lastly, virtually all the published reports on hospitalization and/or reduced physical activity as a treatment for preterm labor have reached conclusions similar to those of our study.2,6–8
Recommending hospitalization for women with arrested preterm labor raises 2 interrelated issues. First, is decreased physical activity beneficial, and second, is hospitalization necessary for this purpose? Bedrest is one of the most often prescribed interventions during pregnancy, yet one of the least studied.6 In 1994, Goldenberg and colleagues2 reviewed the available literature on bedrest in pregnancy and concluded that they could find no evidence supporting or refuting the benefit of either bedrest or hospitalization in women threatening preterm delivery. More recently, Sosa and associates6 used the Cochrane Database to search for trials on the efficacy of bedrest and/or hospitalization and found only one study.7 Data from this study were analyzed to compare bedrest for prevention of preterm birth in 432 women with 834 women without bedrest, and no benefits were found. Goulet and colleagues8 randomized 250 Canadian women to either home care or hospitalization after treatment of an acute episode of preterm labor and also found no benefits for hospitalization. Based upon the information available in the literature and our experience, we see no alternative but to conclude that hospitalization is unnecessary in the management of women with arrested preterm labor, singleton pregnancy, and intact fetal membranes.
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Footnotes |
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The authors thank Ellen Taliaferro for her assistance with the study concept and design.
Address reprint requests to: Nicole P. Yost, MD, University of Texas Southwestern Medical Center, Department of Obstetrics and Gynecology, 5323 Harry Hines Boulevard, Dallas, TX 75390-9032; e-mail: nicole.yost{at}utsouthwestern.edu.
doi:10.1097/01.AOG.0000164466.06180.ad
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REFERENCES |
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2. Goldenberg RL, Cliver SP, Bronstein J, Cutter GR, Andrews WW, Mennemeyer ST. Bed rest in pregnancy. Obstet Gynecol 1994;84:131–6.
3. McIntire DD, Bloom SL, Casey BM, Leveno KJ. Birth weight in relation to morbidity and mortality among newborn infants. N Engl J Med 1999;340:1234–8.
4. Cox SM, Sherman ML, Leveno KJ. Randomized investigation of magnesium sulfate for prevention of preterm birth. Am J Obstet Gynecol 1990;163:767–72.[Medline]
5. Meis PJ, Klebanoff M, Thom E, Dombrowski MP, Sibai B, Moawad AH, et al. Prevention of recurrent preterm delivery by 17 alpha-hydroxyprogesterone caproate. N Engl J Med 2003;348:2379–85.
6. Sosa C, Althabe F, Belizan J, Bergel E. Bed rest in singleton pregnancies for preventing preterm birth (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Oxford: Update Software.
7. Hobel CJ, Ross MG, Bemis RL, Bragonier JR, Nessim S, Sandhu M, et al. The West Los Angeles Preterm Birth Prevention Project. I. Program impact on high- risk women. Am J Obstet Gynecol 1994;170:54–62.[Medline]
8. Goulet C, Gevry H, Lemay M, Gauthier RJ, Lepage L, Fraser W, et al. A randomized clinical trial of care for women with preterm labour: home management versus hospital management. CMAJ 2001;164:985–91.
This article has been cited by other articles:
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  Other articles noted Evid. Based Med., December 1, 2005; 10(6): 191 - 192. [Full Text] [PDF]
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 R. L. Goldenberg Arrested Preterm Labor: Do the Data Support Home or Hospital Care? Obstet. Gynecol., July 1, 2005; 106(1): 3 - 5. [Full Text] [PDF]
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