A Pilot Study: High Versus Low Oxytocin Dosing for Induction of Labor in Pregnant Patients With Obesity (HILIO-PILOT)

The HILIO Trial: High vs. Low Oxytocin Dosing for Induction of Labor in Pregnant Patients With Obesity- PILOT STUDY

Pregnant patients with obesity are more likely to undergo induction of labor and have a higher risk of failed induction compared to patients with normal weight. The association between maternal obesity and labor dysfunction leading to cesarean delivery is poorly understood. Oxytocin is the mostly common medication used in induction of labor, yet optimal dosing of this medication is unknown. Studies have suggested that patients with obesity may be less responsive to oxytocin. This trial will compare a high and low dose oxytocin dosing regimen for the induction of labor in women with obesity.

Study Overview

• Status: Completed
• Conditions: Pregnant Patients With Obesity
• Intervention / Treatment: Drug: High-dose oxytocin; Drug: Low-dose oxytocin

Detailed Description

This study is a pragmatic single center randomized, double blinded controlled trial. Nulliparous women with a pre-pregnancy body mass index (BMI) ≥30 kg/m2 undergoing induction of labor at ≥37 weeks' gestation will be eligible for enrollment. Women will be randomly allocated to receive oxytocin using either a high-dose or low-dose regimen. Patients, providers, and research staff will be blinded to the dosing regimen. All other aspects of obstetric management will be at the discretion of the patient's clinical care team.

Postpartum maternal, neonatal, and delivery outcomes will be collected. Postpartum data through hospital discharge will be collected from the medical record. Information about complications following hospital discharge through 6 weeks after delivery will be collected during a research follow-up telephone call performed 6-8 weeks following delivery.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Ohio
    • Columbus, Ohio, United States, 43210
      • The Ohio State University Wexner Medical Center OB/GYN Maternal and Fetal Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Nulliparity
2. Maternal age >18 years
3. Gestational age ≥37w0d
4. Induction of labor, defined as initiation of labor with medication or intracervical Foley catheter in a patient without observed spontaneous cervical change and <6 contractions per hour (average of one contraction every 10 minutes) at the time of initial presentation. Women with prelabor rupture of membranes (PROM) can be included if the other criteria are also met with regards to cervical dilation and contractions.
5. Singleton gestation
6. Cephalic presentation
7. Indication for oxytocin use in the first stage of labor
8. No contraindication to labor or vaginal delivery
9. Pre-pregnancy BMI ≥30 kg/m2 based on patient report and confirmed by pre-pregnancy or first trimester weight as recorded in the medical record
10. Cervical dilation ≤4 cm at time of initiation of induction

Exclusion Criteria:

1. Fetal demise
2. Major fetal congenital malformation or known chromosomal abnormality
3. Prior uterine surgery (e.g., cesarean, myomectomy)
4. Non-reassuring fetal wellbeing as indication for induction
5. Intraamniotic infection suspected or diagnosed prior to randomization
6. Non-English
7. Multifetal gestation
8. Gestational age <37 weeks
9. Spontaneous labor
10. Cervical dilation > 4 cm at initiation of induction
11. Initiation of oxytocin in the second stage of labor
12. Use of oxytocin prior to randomization or planned use of oxytocin with foley catheter for cervical ripening
13. Fetal malpresentation
14. Estimated fetal weight >4500 g in a patient with diabetes, or estimated fetal weight >5000 g in a non-diabetic patient
15. Abnormal placentation (e.g. previa, suspected placenta accreta spectrum)
16. Physician/provider or patient refusal

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High-dose oxytocin regimen; Starting dose 6 mU/min and increased by 6 mU/min every 30 minutes until adequate contractions achieved, at the discretion of the obstetric providers.	Drug: High-dose oxytocin; Starting dose 6 mU/min and increased by 6 mU/min every 30 minutes until adequate contractions achieved, at the discretion of the obstetric providers.
Experimental: Low-dose oxytocin regimen; Starting dose 2 mU/min and increased by 2 mU/min every 30 minutes until adequate contractions achieved, at the discretion of the obstetric providers.	Drug: Low-dose oxytocin; Starting dose 2 mU/min and increased by 2 mU/min every 30 minutes until adequate contractions achieved, at the discretion of the obstetric providers.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Number of Participants Delivered by Cesarean	Until delivery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of Time From Start of Induction to Delivery	Time from start of induction with medication or Foley catheter until delivery	From start of induction to delivery
Duration of the First Stage of Labor	Time from start of labor to complete dilation	From start of induction to delivery
Occurrence of Tachysystole	Defined as more than 5 contractions in 10 minutes averaged over 30 minutes	From start of induction to delivery
Incidence of Uterine Rupture	Defined as a complete disruption of all uterine layers including serosa	From start of induction to delivery
Incidence of Clinical Chorioamnionitis	Defined based on clinical diagnosis as documented by the clinical care team	From start of induction thorough delivery
Incidence of Postpartum Maternal Infectious Morbidity	Defined as a composite outcome of endomyometritis, puerperal sepsis, or surgical site infection as documented in the the clinical record	Within 6 weeks following delivery
Incidence of Maternal Death		Within 6 weeks of delivery
Incidence of Immediate Postpartum Hemorrhage	Defined as >1000 mL of blood loss within 24 hours of delivery	Within 24 hours of delivery
Incidence of Maternal Blood Transfusion	Defined as need for blood transfusion	From randomization through hospital discharge up to 6 weeks portpartum
Incidence of Maternal ICU Admission		From randomization through 6 weeks postpartum
Incidence of Composite Neonatal Morbidity Outcomes	Apgar score <5 at 5 min, arterial cord pH <7.0 or base deficit >12 mmol/dL, perinatal death	Within 6 weeks of delivery
Incidence of NICU Admission		Within 6 weeks of delivery
Maternal Length of Stay	Duration of hospitalization for delivery	Within 6 weeks of delivery
Neonatal Length of Stay	Duration of birth hospitalization	Within 6 weeks of delivery
Perception of the Labor, Birth, and Postpartum Experience	Patient perception as measured using the validated Childbirth Perception Scale. This is a 12-item instrument developed to assess a patient's perception of the labor and delivery experience. Each item is formatted on a four-point scale ranging from 0 to 3. The overall range in total score is 1-36 with higher scores indicating a less positive perception.	Assessed within 12-96 hours after delivery
Labor Agentry Score	Patient perception of labor agentry as measured using validated Labor Agentry Scale. This 29-item tool was developed to assess a patient's expectancies and experiences with control in labor. Each item is scored 1 to 7. Overall total score can range from 29-201 with higher scores indicated greater perceived control during childbirth.	Assessed within 12-96 hours after delivery

Collaborators and Investigators

• Sponsor: Ohio State University

Study record dates

Study Major Dates

• Study Start (Actual): April 6, 2022
• Primary Completion (Actual): September 18, 2022
• Study Completion (Actual): October 28, 2022

Study Registration Dates

• First Submitted: February 25, 2022
• First Submitted That Met QC Criteria: March 16, 2022
• First Posted (Actual): March 22, 2022

Study Record Updates

• Last Update Posted (Actual): November 29, 2023
• Last Update Submitted That Met QC Criteria: November 8, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Keywords: Oxytocin; Induction of labor; Pregnant patients with obesity
• Additional Relevant MeSH Terms: Overnutrition; Nutrition Disorders; Overweight; Body Weight; Obesity; Physiological Effects of Drugs; Reproductive Control Agents; Oxytocics; Oxytocin
• Other Study ID Numbers: 2021H0432

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