Misoprostol for Induction of Labor in Obese Women: Comparison Between 25 and 50 mcg Oral Administration

Misoprostol for Induction of Labor in Obese Women: Comparison Between 25 and 50 mcg Oral Administration - a Randomized Trial

In recent decades, obesity has become a prevalent issue in Portugal, with 38.6% and 13.8% of the population being overweight or obese, respectively. Obese pregnant women have a higher rate of obstetric complications, including hypertensive complications, gestational diabetes and fetal macrosomia, leading to increased induction of labor (IOL) and cesarean section (CS) rates. To determine the effect of increasing oral misoprostol dose on CS rate in obese pregnant women undergoing IOL, a randomized controlled trial with a sample size of 114 cases in each group was calculated to detect a 15% difference in CS rate. The primary objective is to determine the effect of increasing oral misoprostol dose, with secondary goals being to compare successful IOL rates and their relationship with oral misoprostol dose, as well as to evaluate tolerability and side effects in relation to different doses of oral misoprostol.

Study Overview

• Status: Recruiting
• Conditions: Obesity; Pregnancy; Cesarean Section; Labor, Induced
• Intervention / Treatment: Drug: Misoprostol 25 mcg; Drug: Misoprostol 50 mcg

Detailed Description

The prevalence of obesity has increased dramatically in recent decades, with implications for women of reproductive age and changes in obstetric and perinatal outcomes. In Portugal, it is estimated that 38.6 per cent and 13.8 per cent of the population are overweight or obese, respectively. Compared with women of normal weight, obese pregnant women have a higher rate of obstetric complications. These include hypertensive complications, gestational diabetes and fetal macrosomia. These factors lead to an increased need for IOL before the end of the pregnancy and, consequently, to a reduced degree of cervical dilatation prior to IOL. In addition, the above-mentioned co-morbidities are associated with a higher rate of CS. For all these reasons, obese women have higher IOL and CS rates. The literature also confirms that the degree of obesity is directly related to IOL failure. In some studies, the rate of failed induction is 20.2% and 24.2% in women with obesity grades I and II, respectively. However, few studies have been conducted to determine which IOL agents most commonly induce vaginal labour in obese women, and no studies have defined the most appropriate dose for maternal BMI.

This study provides a breakthrough in understanding the mechanism of labour and response to misoprostol in obese women, as there is a lack of prospective human studies in this area.

Sample size calculation was based on CS rate in obese versus non-obese groups as the primary outcome. According to previous studies, a 22% CS rate in non-obese pregnant women undergoing IOL was calculated, with a between-groups difference of 15% on CS rates being considered clinically significant. Therefore, we set the power at 80%, the alpha error at 0.05 and the ratio of the two study groups at 1:1. Accordingly, 114 cases were needed in each group to detect 15% difference in CS rate.

Primary objective: To determine the effect of increasing oral misoprostol dose on CS rate in obese pregnant women undergoing IOL.

Secondary goals: Comparison of successful IOL rates and their relationship with oral misoprostol dose. Evaluation of tolerability and side effects in relation to different doses of oral misoprostol.

• Study Type: Interventional
• Enrollment (Estimated): 228
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Iolanda Ferreira; Phone Number: +351 239 403 060; Email: 10862@chuc.min-saude.pt

Study Locations

• Portugal
  • Coimbra, Portugal, 3000-157
    • Recruiting
    • Iolanda João Mora Cruz de Freitas Ferreira
    • Contact: Iolanda Ferreira; Email: 10862@chuc.min-saude.pt

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• BMI ≥ 30 kg/m2 recorded based on maternal weight at preconception or in the first trimester
• Singleton live gestation with vertex presentation
• Pregnancies followed in our institution with sonographic confirmation of gestational age in the first trimester
• Obstetrical indication for labor induction
• Bishop score of <5 at the time of induction of labor

Exclusion Criteria:

• Underweight and normal weight women (BMI <30 kg/m2)
• Known hypersensitivity to prostaglandins
• Preterm gestations (< 37 weeks)
• Multiple gestation
• Women who cannot give their informed consent
• Contraindications for vaginal delivery
• Previous c-section or uterine scar due to previous gynecological surgery
• Maternal or fetal pathology (for example: fetal indications: non-reassuring fetal status - intra-uterine growth restriction with abnormal umbilical doppler, abnormal fetal cardiac rhythm; stillbirth; or maternal/pregnancy related indications such as placenta previa)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Misoprostol 25 mcg; Participants received misoprostol 25 mcg every 2 hours until the active stage of labour was attained or failed induction was diagnosed	Drug: Misoprostol 25 mcg; Misoprostol 50 mcg every 2 hours
Experimental: Misoprostol 50 mcg; Participants received misoprostol 25 mcg matching misoprostol 50 mcg every 2 hours until the active stage of labour was attained or failed induction was diagnosed	Drug: Misoprostol 50 mcg; Misoprostol 50 mcg every 2 hours

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cesarean section rates	Calculation in percentage. An average of 22% cesarean section rate in non-obese pregnant women undergoing IOL was determined, with a between-groups difference of 15% on cesarean section rates being considered clinically significant.	Up to 3 days after first misoprostol intake until delivery (vaginal or cesarean section)
Indication for cesarean section	The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine guidelines for caesarean section indications are used. When a caesarean section is performed, it will be classified in mutually exclusive categories. These are: First stage labor dystocia: Yes/No Second stage labor dystocia: Yes/No Abnormal or indeterminate fetal heart rate tracing: Yes/No Failed induction: Yes/No	Delivery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rate of vaginal delivery within 24 hours	Percentage of eutocic or instrumental deliveries that occured within a 24h of the first misoprostol intake	Time of first misoprostol intake until vaginal delivery
Time interval from the first dose of misoprostol to vaginal delivery	Median time in hours	Time of first misoprostol intake until vaginal delivery
Rate of instrumental delivery	Percentage of vaginal deliveries that need instrumentation with ventouse or forceps	Delivery
Time interval from the first dose of misoprostol to cesarean section delivery	Median time in hours	Time of first misoprostol intake until cesarean section delivery
Incidence of misoprostol adverse effects	Tachysystole (defined as at least six uterine contractions in 10 minutes for two consecutive 10-minute periods) and hyperstimulation (defined as the presence of tachysystole or a prolonged uterine contraction lasting 2 or more minutes associated with fetal heart rate abnormalities) will be evaluated	Time of first misoprostol intake until vaginal or cesarean section delivery

Collaborators and Investigators

• Sponsor: Centro Hospitalar e Universitário de Coimbra, E.P.E.

Study record dates

Study Major Dates

• Study Start (Actual): October 15, 2019
• Primary Completion (Estimated): May 31, 2024
• Study Completion (Estimated): June 30, 2024

Study Registration Dates

• First Submitted: April 6, 2023
• First Submitted That Met QC Criteria: May 10, 2023
• First Posted (Actual): May 12, 2023

Study Record Updates

• Last Update Posted (Actual): October 24, 2023
• Last Update Submitted That Met QC Criteria: October 22, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Gastrointestinal Agents; Reproductive Control Agents; Anti-Ulcer Agents; Abortifacient Agents, Nonsteroidal; Abortifacient Agents; Oxytocics; Misoprostol
• Other Study ID Numbers: CHUC-151-17

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No