A Cluster Randomized Trial of Labor Induction With Oral Versus Vaginal Misoprostol

  • End date
    Aug 15, 2024
  • participants needed
  • sponsor
    University of Texas Southwestern Medical Center
Updated on 15 October 2022
vaginal delivery
induction of labor


This study will compare vaginal and oral misoprostol, to determine whether a vaginal misoprostol regimen achieves a higher vaginal delivery rate in a real-world, high-volume setting, and whether this regimen reduces time and oxytocin need on a high-volume Labor and Delivery unit at Parkland Hospital.

Our primary hypothesis is that among women with singleton, term pregnancies, cervical dilation 2cm or less, and indicated labor induction, the rate of vaginal delivery is significantly increased when a standardized vaginal misoprostol regimen is used, compared with a standardized oral misoprostol regimen.


The purpose of this study is to determine whether the use of a standardized vaginal misoprostol regimen will result in a decreased primary cesarean delivery rate among women with a cervical dilation of 2 centimeters of less who require induction of labor at term, compared with the currently used oral misoprostol regimen. We also aim to evaluate oxytocin use, time to delivery, uterine activity, indication for cesarean delivery, intrapartum and postpartum infectious morbidities, excess blood loss at delivery, and adverse neonatal outcomes in the overall population as well as nulliparous women specifically.

This will be a prospective, cluster-randomized clinical trial to compare the rate of vaginal delivery achieved when two standards of care are used across a large population of women with indication for labor induction at Parkland Hospital. Eligible participants will include nulliparous and multiparous women at 37 weeks gestation or greater, with a living, singleton fetus and no major fetal malformations, in cephalic presentation, with intact membranes, no prior uterine scar, who qualify for prostaglandin administration and who have a cervical dilation of 2 centimeters or less, measured at the level of the internal os. Patients with non-reassuring fetal status, active herpes outbreak, a prior uterine scar, or any contraindication to prostaglandins (including 4 or more painful contractions per 10 minutes prior to prostaglandin administration) will be excluded from participation in the study.

Computer-generated cluster randomization will occur on a weekly basis for all study participants, to either the vaginal misoprostol regimen (study group) or to oral misoprostol regimen (control group).

According to the randomization protocol each week, participants will be randomized to either the oral misoprostol standard of care (control group) or vaginal misoprostol standard of care (study group). The study group will receive vaginal misoprostol 25 mcg every 3 hours for a maximum of 5 doses in those who meet criteria for prostaglandin administration. The control group will receive oral misoprostol 100 micrograms given every 4 hours for a maximum of 2 doses. Misoprostol will not be administered to patients who have progressed to active labor, defined as 4 centimeters cervical dilation. Intravenous oxytocin will be administered according to current PHHS protocol for both groups.

No direct contact between the research team and patients will be required, as this is a systematic comparison of two standards of care.

The primary outcome will be the rate of vaginal delivery.

Secondary outcomes will include maternal and neonatal outcomes.

Maternal outcomes will include time to delivery, time (hours) of oxytocin, need for oxytocin, indication for cesarean delivery, labor analgesia, clinical chorioamnionitis, tachysystole, hyperstimulation syndrome, excess estimated blood loss, transfusion at delivery, endometritis, surgical site infection, uterine rupture, and unplanned hysterectomy.

Neonatal outcomes will include meconium-stained amniotic fluid, umbilical cord pH <7.0, 5-minute Apgar <4, neonatal intubation or ventilation in the delivery room, neonatal sepsis, and neonatal intensive care (NICU) admission.

Condition Pregnancy, Labor, Induced
Treatment oral misoprostol, Vaginal misoprostol
Clinical Study IdentifierNCT04755218
SponsorUniversity of Texas Southwestern Medical Center
Last Modified on15 October 2022


Yes No Not Sure

Inclusion Criteria

Nulliparous and multiparous pregnant women
weeks gestation or greater
Living, singleton fetus
No major fetal malformations
Cephalic presentation
No prior uterine scar
Intact fetal membranes
Qualifies for prostaglandin administration according to current Parkland protocol
Have a cervical dilation of 2 centimeters or less, measured at the level of the internal os
Have an indication for induction or attempted induction of labor according to Parkland protocol

Exclusion Criteria

Non-reassuring fetal status
Active herpes outbreak
Prior uterine scar
Contraindication to prostaglandins according to current Parkland protocol (including 4 or more painful contractions per 10 min prior to prostaglandin administration)
Contraindication to vaginal delivery
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