• Time to vaginal delivery [ Time Frame: Following administration of study medication ]
• Rate of Cesarean Section delivery [ Time Frame: Following administration of study medication ]

• Incidence of adverse events ( and comparison of overall safety [ Time Frame: Following administration of study medication ]
• Need for oxytocin, duration of oxytocin use, total dose of oxytocin [ Time Frame: Pre-delivery ]
• Successful cervical ripening using Modified Bishop's Score at 12 hours [ Time Frame: At 12 hours after study drug insertion ]
• Time to onset of active labor [ Time Frame: From study drug insertion to onset active labor ]
• Time to rupture of membranes [ Time Frame: Interval from study drug insertion to ROM ]
• Duration of stay in labor and delivery suite [ Time Frame: While in the study ]
• Duration of stay in hospital for mother and neonate [ Time Frame: While in the study ]

• Incidence of adverse events (including cesarean section) and comparison of overall safety
• Need for oxytocin, duration of oxytocin use, total dose of oxytocin
• Successful cervical ripening using Modified Bishop's Score at 12 hours
• Time to onset of active labor
• Time to rupture of membranes
• Duration of stay in labor and delivery suite
• Duration of stay in hospital for mother and neonate

The purpose of this study is to determine whether the misoprostol vaginal insert (50 mcg and 100 mcg) can safely and effectively speed time to vaginal delivery compared to Cervidil (R) in women who need to have their labor induced.

Induction of labor is required in approximately 20% of pregnant women. Although contractions can be brought on by oxytocin ("pitocin"), some women need help in softening the cervix, or mouth of the womb (uterus), before oxytocin can be started. Prostaglandins have been shown to ripen, or soften, the cervix; at present, the only prostaglandin approved for marketing by FDA for this purpose is dinoprostone. Dinoprostone can be delivered in several ways; one method is to use a polymer vaginal insert that slowly releases the dinoprostone directly to the cervical tissues. This product is called Cervidil (R) and has been marketed for more than 10 years in the United States. Misoprostol is another form of prostaglandin that is approved for protecting the stomach and intestinal lining for patients taking NSAIDs. Misoprostol has also been used by many obstetricians for cervical ripening and inducing contractions, but, it is not approved by FDA for this purpose.

The same company that makes the Cervidil polymer insert has made an insert that will slowly release misoprostol. This study will determine whether this investigational insert containing misoprostol will decrease time to vaginal delivery compared to Cervidil. Two different doses of misoprostol will be tested (50 micrograms and 100 micrograms); each vaginal insert will gradually release a small, controlled amount of misoprostol over up to 24 hours.

Comparator: The Cervidil (R) vaginal insert containing dinoprostone will be the comparator in this study.

• Cervical Ripening
• Labor, Induced

• Drug: Misoprostol vaginal insert 100 mcg
• Drug: Misoprostol vaginal insert 50 mcg
• Drug: Dinoprostone vaginal insert (Cervidil)

• Experimental: Misoprostol vaginal insert 100 mcg over 24h
• Experimental: Misoprostol vaginal insert 50 mcg over 24h
• Active Comparator: Cervidil 10 mg over 24h

• Castaneda CS, Izquierdo Puente JC, Leon Ochoa RA, Plasse TF, Powers BL, Rayburn WF. Misoprostol dose selection in a controlled-release vaginal insert for induction of labor in nulliparous women. Am J Obstet Gynecol. 2005 Sep;193(3 Pt 2):1071-5.
• Rayburn WF, Powers BL, Plasse TF, Carr D, Di Spirito M. Pharmacokinetics of a controlled-release misoprostol vaginal insert at term. J Soc Gynecol Investig. 2006 Feb;13(2):112-7.
• Ewert K, Powers B, Robertson S, Alfirevic Z. Controlled-release misoprostol vaginal insert in parous women for labor induction: a randomized controlled trial. Obstet Gynecol. 2006 Nov;108(5):1130-7.
• Wing DA; Misoprostol Vaginal Insert Consortium. Misoprostol vaginal insert compared with dinoprostone vaginal insert: a randomized controlled trial. Obstet Gynecol. 2008 Oct;112(4):801-12.

Inclusion Criteria:

• Pregnant women at least 36 weeks gestation requiring cervical ripening and induction of labor

Exclusion Criteria:

• No uterine scar (no previous delivery by cesarean section)
• No multiple gestation
• No condition that disallows use of prostaglandins for induction of labor
• No more than 3 previous vaginal births beyond 24 weeks gestation