Combined Misoprostol and Cervical Balloon vs Misoprostol Alone for Induction on the First Day in Primiparas

Efficacy of Intravaginal Misoprostol Combined With Cervical Balloon Versus Misoprostol Alone for Induction of Labor on the First Day in Primiparous Women: A Randomized Controlled Trial

Misoprostol (a prostaglandin E1 analog) is commonly used for cervical ripening and labor induction via vaginal administration. The cervical balloon is another commonly used method that provides mechanical cervical dilation. Both methods are low-cost and widely available. Some meta-analyses have suggested that combined use may shorten the duration of labor, reduce the frequency of tachysystole, and lower NICU admission rates without increasing the risk of cesarean section. However, existing studies are heterogeneous and lack data from Asian populations.

This study is being done to see whether combining two common methods of labor induction-misoprostol (a medicine placed in the vagina) and a cervical balloon (placed in the cervix) on the first day of induction-can shorten the time from the start of induction to delivery in first-time mothers during pregnancy .

Participants will be randomly assigned to one of two groups: one group will receive misoprostol alone (standard care) on the first day of induction, and the other group will receive misoprostol plus a cervical balloon on the first day of induction. The main outcome measured is the time from the start of induction to delivery. The study will also look at safety outcomes, including the rate of cesarean section, maternal complications, and newborn outcomes.

Study Overview

• Status: Not yet recruiting
• Conditions: Primiparous Women
• Intervention / Treatment: Device: Misoprostol plus Cervical Balloon; Drug: Misoprostol

Detailed Description

This is a single-center, randomized, open-label, superiority randomized controlled trial. Participants will be randomly assigned in a 1:1 ratio to either the intervention group (misoprostol plus cervical balloon on the first day of induction) or the control group (misoprostol alone on the first day of induction).

IPRIMARY OUTCOME:

Time from initiation of labor induction to delivery (hours).

SECONDARY OUTCOMES:

Time from induction to amniotomy (min), time from induction to spontaneous membrane rupture (h), time from induction to onset of labor (min), duration of balloon use (min), duration of oxytocin use (min), duration of latent phase (h), duration of first and second stages of labor (min), mode of delivery, degree of perineal laceration, indications for forceps/episiotomy/cesarean section, fetal distress, intrauterine infection, neonatal outcomes (birth weight, Apgar score, umbilical artery pH/BE, NICU admission), and maternal hemoglobin difference before and after delivery. Safety outcomes include placental abruption, septic shock, and severe postpartum hemorrhage.

SAMPLE SIZE:

Based on historical data from 90 primiparous women at Peking University First Hospital (June 2025), the mean induction-to-delivery interval was 39.07 ± 19.92 hours. Assuming an 8-hour reduction in the intervention group, with a two-sided alpha of 0.05, power of 80%, and a 10% dropout rate, each group requires 110 participants (total 220).

STATISTICAL ANALYSIS:

Continuous variables will be compared using t-test or Mann-Whitney U test as appropriate. Categorical variables will be compared using chi-square or Fisher's exact test. Multivariable linear regression and logistic regression will be used for adjusted analyses. Subgroup analyses will be performed by type of hyperglycemia, age, BMI, and baseline Bishop score.

ETHICS AND REGISTRATION:

This study has been approved by the Biomedical Research Ethics Committee of Peking University First Hospital (Approval No. 2025R0393-0002, dated September 25, 2025). The study is registered on ClinicalTrials.gov.

STUDY PERIOD:

June 2026 to December 2026.

• Study Type: Interventional
• Enrollment (Estimated): 220
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Ye Feng, M.D.; Phone Number: 8618001203634; Email: fengye_bjmu@163.com
• Study Contact Backup: Name: Jianhua Niu, M.D.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 20-45 years at delivery
• Singleton pregnancy
• Primiparous
• Cephalic presentation
• Cervical Bishop score ≤ 5
• No history of stillbirth

Exclusion Criteria:

• Multiple pregnancy
• Contraindications to vaginal delivery
• Mental disorders (depression or anxiety)
• Preterm labor (< 37 weeks)
• Intrauterine fetal death
• Previous uterine surgery
• Premature rupture of membranes
• Abnormal fetal heart rate tracing

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Misoprostol Plus Cervical Balloon; Participants receive 25 μg misoprostol placed in the posterior vaginal fornix, combined with a Cervical balloon catheter (80 mL inflation) placed intracervically for 12-24 hours on the first day of induction. Misoprostol may be repeated up to 3-4 times based on uterine contraction response.	Device: Misoprostol plus Cervical Balloon; A Cervical balloon with 80 mL sterile water inflation placed intracervically for mechanical cervical dilation. The balloon is left in place for up to 12-24 hours or until spontaneous expulsion.
Active Comparator: Misoprostol Alone; Participants receive 25 μg misoprostol placed in the posterior vaginal fornix alone on the first day of induction. Misoprostol may be repeated up to 3-4 times based on uterine contraction response.	Drug: Misoprostol; 25 μg misoprostol tablet placed in the posterior vaginal fornix for cervical ripening and labor induction on the first day. May be repeated up to 3-4 times based on uterine contraction response (monitored every 2-4 hours).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time from initiation of labor induction to delivery	Time in hours from the start of labor induction (placement of first dose of misoprostol or Foley balloon) to vaginal delivery or cesarean section.	Time from initiation of induction measures on the first day of induction to delivery (control group: time of first misoprostol placement; intervention group: time of cervical balloon and misoprostol placement).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time from Induction to Amniotomy	Duration from the start of induction (placement of misoprostol or balloon+misoprostol) to the performance of amniotomy, measured in minutes.	From start of induction to amniotomy
Time from Induction to Spontaneous Membrane Rupture	Duration from the start of induction to spontaneous rupture of fetal membranes, measured in hours.	From start of induction to spontaneous rupture
Time from Induction to Onset of Labor	Duration from the start of induction to the establishment of regular painful uterine contractions with cervical opening, measured in minutes.	From start of induction to onset of labor
Duration of Balloon Use	Total time the cervical balloon remains in place (from insertion to removal), measured in minutes.	From balloon insertion to removal, assessed during the induction period (up to 24 hours).
Duration of Oxytocin Use	Total duration of oxytocin administration during labor, measured in minutes.	From start to stop of oxytocin infusion, assessed during labor
Duration of Latent Phase of Labor	Time from onset of labor to cervical dilation of 5 cm, measured in hours.	From onset of labor to active phase, assessed during labor
Duration of First and Second Stages of Labor	Time from full cervical dilation (first stage) to delivery of the newborn (second stage), measured in minutes	From full dilation to delivery, assessed during the second stage
Mode of Delivery	Categorization of delivery as spontaneous vaginal, vacuum/forceps-assisted, or cesarean section.	At the time of delivery.
Degree of Perineal Laceration	Severity of perineal tears classified as first-, second-, third-, or fourth-degree.	Immediately after vaginal delivery.
Indications for Forceps/Episiotomy/Cesarean Section	Clinical reasons for performing forceps delivery, episiotomy, or cesarean section (e.g., fetal distress, arrest of labor).	At the time of the operative intervention (during labor/delivery).
Fetal Distress	Presence of fetal distress diagnosed by abnormal fetal heart rate patterns or acidemia during labor.	During labor, assessed up to delivery.
Intrauterine Infection	Clinical or histologic diagnosis of chorioamnionitis or endometritis during or after delivery.	During labor and up to 48 hours postpartum.
Neonatal Birth Weight	Weight of the newborn measured immediately after delivery, in grams.	At delivery (immediately after birth).
Apgar Score	Apgar score assessed at 1 and 5 minutes after birth, range 0-10.	At 1 and 5 minutes after birth.
Umbilical Artery pH and Base Excess	pH and base excess (BE) values measured in umbilical artery blood at delivery.	Immediately after delivery (from cord blood).
NICU Admission	Whether the newborn is admitted to the NICU after delivery.	After birth.
Maternal Hemoglobin Difference	Difference between pre-delivery (baseline) and post-delivery hemoglobin levels, measured in g/dL.	Baseline (before induction) and within 24-48 hours after delivery.
Placental Abruption	Premature separation of the placenta from the uterine wall, diagnosed clinically or by ultrasound.	During labor and delivery
Septic Shock	Severe infection leading to circulatory failure, requiring vasopressors.	Before or after birth
Severe Postpartum Hemorrhage	Estimated blood loss ≥1000 mL or requiring transfusion or surgical intervention.	Within 24 hours after delivery.

Collaborators and Investigators

• Sponsor: Peking University First Hospital
• Investigators: Principal Investigator: Ye Feng, M.D., Peking University First Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: June 29, 2026
• First Submitted That Met QC Criteria: July 7, 2026
• First Posted (Actual): July 8, 2026

Study Record Updates

• Last Update Posted (Actual): July 8, 2026
• Last Update Submitted That Met QC Criteria: July 7, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: misoprostol; labor induction; foley balloon catheter
• Additional Relevant MeSH Terms: Fatty Acids; Lipids; Biological Factors; Prostaglandins, Synthetic; Prostaglandins; Eicosanoids; Fatty Acids, Unsaturated; Autacoids; Inflammation Mediators; Prostaglandins E, Synthetic; Misoprostol
• Other Study ID Numbers: 2025R0393-0002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No