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Activity Restriction Among Women With a Short Cervix

Grobman, William A. MD, MBA; Gilbert, Sharon A. MBA, PhD; Iams, Jay D. MD; Spong, Catherine Y. MD; Saade, George MD; Mercer, Brian M. MD; Tita, Alan T. N. MD, PhD; Rouse, Dwight J. MD; Sorokin, Yoram MD; Leveno, Kenneth J. MD; Tolosa, Jorge E. MD, MSCE; Thorp, John M. MD; Caritis, Steve N. MD; Peter Van Dorsten, J. MD

doi: 10.1097/AOG.0b013e3182917529
Original Research

OBJECTIVE: To estimate determinants of and outcomes associated with activity restriction among women with a short cervix.

METHODS: This was a secondary analysis of a randomized trial of 17-α hydroxyprogesterone caproate for prevention of preterm birth among nulliparous women with singleton gestations and cervices less than 30 mm by midtrimester ultrasonography. Women were asked weekly whether they had been placed on pelvic, work, or nonwork rest. “Any activity restriction” was defined as being placed on any type of rest. Factors associated with any activity restriction were determined and the association between preterm birth and activity restriction was estimated with multivariable logistic regression.

RESULTS: Of the 657 women in the trial, 646 (98%) responded to questions regarding activity restriction. Two hundred fifty-two (39.0%) were placed on any activity restriction at a median of 23.9 weeks (interquartile range 22.6–27.9 weeks). Women on activity restriction were older, more likely to have private insurance, less likely to be Hispanic, had a shorter cervical length, and were more likely to have funneling and intra-amniotic debris. Preterm birth at less than 37 weeks of gestation was more common among women placed on activity restriction (37% compared with 17%, P<.001). After controlling for potential confounding factors, preterm birth remained more common among those placed on activity restriction (adjusted odds ratio 2.37, 95% confidence interval 1.60–3.53). Results were similar for preterm birth at less than 34 weeks of gestation.

CONCLUSION: Activity restriction did not reduce the rate of preterm birth in asymptomatic nulliparous women with a short cervix.


Supplemental Digital Content is Available in the Text.Activity restriction is recommended for more than one third of women with a cervix less than 30 mm and is associated with an increased risk of preterm birth.

From the Departments of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois, The Ohio State University, Columbus, Ohio, University of Texas Medical Branch, Galveston, Texas, Case Western Reserve University–MetroHealth Medical Center, Cleveland, Ohio, University of Alabama at Birmingham, Birmingham, Alabama, Brown University, Providence, Rhode Island, Wayne State University, Detroit, Michigan, University of Texas Southwestern Medical Center, Dallas, Texas, Oregon Health & Science University, Portland, Oregon, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, University of Pittsburgh, Pittsburgh, Pennsylvania, and Medical University of South Carolina, Charleston, South Carolina; the George Washington University Biostatistics Center, Washington, DC; and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.

Corresponding author: William A. Grobman, MD, MBA, 250 East Superior Street, Suite 05-2175, Chicago, IL 60611; e-mail:

Supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) (HD21410, UL1 RR024153, UL1 TR000005; HD27869, HD27915, HD27917, HD34116, HD34208, 5UL1RR025764, HD36801, HD40500, HD40512, HD40544, M01 RR00080, UL1 RR024989 (NCRR), HD40545, HD40560, HD40485, HD53097, HD53118) and does not necessarily represent the official views of the National Center for Research Resources, NICHD, or National Institutes of Health.

Financial Disclosure The authors did not report any potential conflicts of interest.

Dr. Spong, and Dr. Rouse, Associate Editors of Obstetrics & Gynecology, were not involved in the review or decision to publish this article.

* For a list of other members of the NICHD MFMU, see the Appendix online at

Presented at the Society for Maternal-Fetal Medicine meeting, February 11–16, 2013, San Francisco, California.

The authors thank Gail Mallett, RN, BSN, CCRC, and Cynthia Milluzzi, RN, for protocol development and coordination between clinical research centers; and Elizabeth Thom, PhD, for protocol and data management and statistical analysis.

© 2013 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.