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Disclaimer: CME certification for these activities has expired. All information is pertinent to the timeframe in which it was released.

New Developments in Cervical Ripening

To update obstetricians/gynecologists on the new developments in cervical ripening.

This activity is designed for obstetricians/gynecologists. No prerequisites required.

The Johns Hopkins University School of Medicine takes responsibility for the content, quality, and scientific integrity of this CME activity. At the conclusion of this activity, participants should be able to:

  • Understand patient selection in the induction of labor.
  • Demonstrate an increased knowledge of cervical/pelvic scoring systems, fetal fibronectin, and other indications.
  • Understand the issues surrounding induction agents and relevant research.

The Johns Hopkins University School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Johns Hopkins University School of Medicine designates this educational activity for a maximum of 2 category 1 credits toward the AMA Physician's Recognition Award. Each physician should claim only those credits that he/she actually spent in the activity. The estimated time to complete this educational activity: 2 hours.

Release date: October 15, 2005.
Expiration date: October 15, 2007.

The opinions and recommendations expressed by faculty and other experts whose input is included in this program are their own. This enduring material is produced for educational purposes only. Use of The Johns Hopkins University School of Medicine name implies review of educational format, design, and approach. Please review the complete prescribing information of specific drugs or combinations of drugs, including indications, contraindications, warnings, and adverse effects, before administering pharmacologic therapy to patients.

This program is supported by an educational grant from Forest Laboratories.

Full Disclosure Policy Affecting CME Activities:
As a provider accredited by the Accreditation Council for Continuing Medical Education (ACCME), it is the policy of the Johns Hopkins University School of Medicine to require the disclosure of the existence of any significant financial interest or any other relationship a faculty member or a sponsor has with the manufacturer(s) of any commercial product(s) discussed in an educational presentation. The Program Directors and Participating Faculty reported the following:


Frank Witter, MD
Associate Professor
Department of Obstetrics and Oncology
Johns Hopkins School of Medicine
Batlimore, Maryland
Dr Witter reports having no financial or advisory relationships with corporate organizations related to this activity.


Lawrence Devoe, MD
Department of Obstetrics and Gynecology
Medical College of Georgia
August, Georgia
Dr Devoe reports having no financial or advisory relationships with corporate organizations related to this activity.

Notice: The audience is advised that articles in this CME activity contain no reference(s) to unlabeled or unapproved uses of drugs or devices.

Drs Witter and Devoe—misoprostol and Foley catheters.

Advanced Studies in Medicine provides disclosure information from contributing authors, lead presenters, and participating faculty. Advanced Studies in Medicine does not provide disclosure information from authors of abstracts and poster presentations. The reader shall be advised that these contributors may or may not maintain financial relationships with pharmaceutical companies.

New Developments in Cervical Ripening
Frank Witter, MD*

Induction of labor is indicated when the benefits to the mother or the fetus outweigh the benefits of continuing the pregnancy. Induction of labor involves a complex set of interventions that defies routine and presents several choices and challenges for clinicians and mothers. It is a process that is deemed successful when it initiates uterine contractions, progressively dilates and effaces the cervix, and leads to the normal vaginal birth of the baby with no maternal complications. Induction is deemed a failure when active labor is not achieved or cesarean delivery is required. There is no magic bullet that will guarantee the success of an induced trial of labor, but evidence-based clinical practice can promote optimal decision making.

In 2002, 800 000 women in the United States underwent induction of labor, representing a little more than 20% of all deliveries. This rate of induction of labor is more than double the rate of 9% reported in 1989.1 This rising trajectory of labor induction has not yet found a plateau. Wide geographic variations in induction rates, from 11% in Hawaii to 42% in Wisconsin, have been noted but have not been adequately explained.2,3

The increasing use of labor induction has been supported by the expansion of medical indications for delivery before the onset of spontaneous labor thanks to advances in obstetrical science. Because of social and economic change, the indications for elective induction have also broadened. During the past decade, the increase in the rate of medically indicated inductions was lower than the overall increase (70% vs 100%).2 This suggests that the rate of increase of elective inductions outpaces that of inductions that are medically indicated. Elective induction of labor has become more popular, as timed delivery can provide more patient/physician convenience. Other contributing factors include the ready availability of effective cervical ripeners, medicolegal issues, patient demand, and financial gain.4

This trend over time has important implications for clinical practice because, as several investigators have reported, elective induction consistently results in a 2- or 3-fold increase in the risk of cesarean delivery.5,6 The rate of cesarean delivery reached an all-time high of 28% in 2003 in the United States, more than quintuple the rate of 5% recorded in 1970.7,8 Although the factors contributing to the rising rate of cesarean delivery are multiple and complex, increased use of labor induction makes a major contribution to this outcome. Two particular groups of patients, nulliparas and multiparas who have undergone previous cesarean birth, demand special attention.

Nulliparas contribute more to the rising rate of cesarean sections than any other class of patients. When compared to nulliparas who enter labor spontaneously, nulliparous women undergoing induction are more than twice as likely to have trials of labor that end in cesarean delivery.9 Numerous studies also suggest the existence of identifiable factors that can help clinicians predict success and avoid failed induction.5,10 Nulliparas disproportionately feed the growing pool of gravid patients with previous cesarean sections—estimated to comprise 10% to 15% of all pregnant women. This rate is likely to grow and may result in the need for obstetricians to manage patients desiring vaginal birth after cesarean section (VBAC) on a more frequent basis.11

Vaginal birth after cesarean section accounted for 3% of deliveries after previous cesarean section in the United States in 1981 and rose to 31% in 1998.12 Medicolegal concerns about uterine rupture and maternal and perinatal morbidity have since reduced the rate substantially to 12.7%, as reported in 2002.8 The migration of VBAC into most clinical practices requires special consideration. Current literature has identified several risks associated with VBAC, and it suggests that any exogenous induction agent, including oxytocin, is an independent risk factor for uterine rupture in patients with a pre-existing uterine scar. The absolute risk of uterine rupture may be small, but it is one of the most serious obstetric emergencies and potentially life-threatening to the mother and fetus.13

This issue of Advanced Studies in Medicine is intended to assist clinicians in building the best case for success before deciding to induce labor. It is intended to be an update and to review the evidence that supports the decision to induce labor, in addition to the decision not to induce labor. Cervical ripening can influence the successful outcome of induction, and obstetricians have an array of mechanical and pharmacologic methods to prepare the cervix for labor with an unfavorable Bishop score. However, the most important variable influencing successful labor induction is appropriate patient selection. Recent studies provide new evidence to weigh when selecting patients for induction, making optimal clinical decisions as the trial of labor progresses, and, in the long term, affecting an appropriate rate of cesarean delivery.


1. Martin JA, Hamilton BE, Sutton PD, et al. Births: final data for 2002. Natl Vital Stat Rep. 2003;52:1-114.
2. Rayburn WF, Zhang J. Rising rates of labor induction: present concerns and future strategies. Obstet Gynecol. 2002;100:164-167.
3. Cunningham GF. Williams Obstetrics. 22nd ed. New York, NY: McGraw Hill; 2005.
4. Lockwood CJ. Confronting the professional liability crisis. Contemp Obstet Gynecol. 2002:13.
5. Maslow AS, Sweeny AL. Elective induction of labor as a risk factor for cesarean delivery among low-risk women at term. Obstet Gynecol. 2000;95:917-922.
6. Yeast JD, Jones A, Poskin M. Induction of labor and the relationship to cesarean delivery: a review of 7001 consecutive inductions. Am J Obstet Gynecol. 1999;180:628-633.
7. Hamilton BE, Martin JA, Sutton PD. Births: preliminary data for 2003. Natl Vital Stat Rep. 2004;53:1-17.
8. Hamilton BE, Martin JA, Sutton PD. Births: preliminary data for 2002. Natl Vital Stat Rep. 2003;51:1-20.
9. Seyb ST, Berka RJ, Socol ML, Dooley SL. Risk of cesarean delivery with elective induction of labor at term in nulliparous women. Obstet Gynecol. 1999;94:600-607.
10. Vrouenraets FP, Roumen FJ, Dehing CJ, et al. Bishop score and risk of cesarean delivery after induction of labor in nulliparous women. Obstet Gynecol. 2005;105:690-697.
11. Wing DA, Park MR, Paul RH. Vaginal birth after cesarean section: selection and management. Clin Obstet Gynecol. 1999;42:836-848.
12. Menacker F, Curtin SC. Trends in cesarean birth and vaginal birth after previous cesarean 1991-99. Natl Vital Stat Rep. 2001;49:1-16.
13. Landon MB, Hauth JC, Leveno KJ, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med. 2004;351:2581-2589.

*Associate Professor, Department of Obstetrics and Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland.

Address correspondence to: Frank Witter, MD, Associate Professor, Department of Obstetrics and Oncology, Johns Hopkins School of Medicine, East Baltimore Campus, Phipps 228, 600 North Wolfe Street, Baltimore, MD 21287.

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