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NCT Number: NCT07690007

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

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.

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Key information

Conditions

Primiparous Women

Age range

20 year–45 year

Sex eligibility

Female

Study type

Interventional

Phase

Phase 4

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Misoprostol

Drug

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).

Misoprostol plus Cervical Balloon

Device

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.

Primary outcomes

  1. Time from initiation of labor induction to delivery

    Time frame: 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).

    Time in hours from the start of labor induction (placement of first dose of misoprostol or Foley balloon) to vaginal delivery or cesarean section.

Secondary outcomes

  1. Time from Induction to Amniotomy

    Time frame: From start of induction to amniotomy

    Duration from the start of induction (placement of misoprostol or balloon+misoprostol) to the performance of amniotomy, measured in minutes.

  2. Time from Induction to Spontaneous Membrane Rupture

    Time frame: From start of induction to spontaneous rupture

    Duration from the start of induction to spontaneous rupture of fetal membranes, measured in hours.

  3. Time from Induction to Onset of Labor

    Time frame: From start of 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.

  4. Duration of Balloon Use

    Time frame: From balloon insertion to removal, assessed during the induction period (up to 24 hours).

    Total time the cervical balloon remains in place (from insertion to removal), measured in minutes.

  5. Duration of Oxytocin Use

    Time frame: From start to stop of oxytocin infusion, assessed during labor

    Total duration of oxytocin administration during labor, measured in minutes.

  6. Duration of Latent Phase of Labor

    Time frame: From onset of labor to active phase, assessed during labor

    Time from onset of labor to cervical dilation of 5 cm, measured in hours.

  7. Duration of First and Second Stages of Labor

    Time frame: From full dilation to delivery, assessed during the second stage

    Time from full cervical dilation (first stage) to delivery of the newborn (second stage), measured in minutes

  8. Mode of Delivery

    Time frame: At the time of delivery.

    Categorization of delivery as spontaneous vaginal, vacuum/forceps-assisted, or cesarean section.

  9. Degree of Perineal Laceration

    Time frame: Immediately after vaginal delivery.

    Severity of perineal tears classified as first-, second-, third-, or fourth-degree.

  10. Indications for Forceps/Episiotomy/Cesarean Section

    Time frame: At the time of the operative intervention (during labor/delivery).

    Clinical reasons for performing forceps delivery, episiotomy, or cesarean section (e.g., fetal distress, arrest of labor).

  11. Fetal Distress

    Time frame: During labor, assessed up to delivery.

    Presence of fetal distress diagnosed by abnormal fetal heart rate patterns or acidemia during labor.

  12. Intrauterine Infection

    Time frame: During labor and up to 48 hours postpartum.

    Clinical or histologic diagnosis of chorioamnionitis or endometritis during or after delivery.

  13. Neonatal Birth Weight

    Time frame: At delivery (immediately after birth).

    Weight of the newborn measured immediately after delivery, in grams.

  14. Apgar Score

    Time frame: At 1 and 5 minutes after birth.

    Apgar score assessed at 1 and 5 minutes after birth, range 0-10.

  15. Umbilical Artery pH and Base Excess

    Time frame: Immediately after delivery (from cord blood).

    pH and base excess (BE) values measured in umbilical artery blood at delivery.

  16. NICU Admission

    Time frame: After birth.

    Whether the newborn is admitted to the NICU after delivery.

  17. Maternal Hemoglobin Difference

    Time frame: Baseline (before induction) and within 24-48 hours after delivery.

    Difference between pre-delivery (baseline) and post-delivery hemoglobin levels, measured in g/dL.

  18. Placental Abruption

    Time frame: During labor and delivery

    Premature separation of the placenta from the uterine wall, diagnosed clinically or by ultrasound.

  19. Septic Shock

    Time frame: Before or after birth

    Severe infection leading to circulatory failure, requiring vasopressors.

  20. Severe Postpartum Hemorrhage

    Time frame: Within 24 hours after delivery.

    Estimated blood loss ≥1000 mL or requiring transfusion or surgical intervention.

Study contacts

Contact information is provided by the study sponsor or research team.

Jianhua Niu, M.D.

CONTACT

Ye Feng, M.D.

CONTACT

[email protected]

8618001203634

Sponsors and collaborators

Lead sponsor

Peking University First Hospital

Other

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jul 8, 2026
Registry last updated
Jul 8, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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