A Pilot Study: High Versus Low Oxytocin Dosing for Induction of Labor in Pregnant Patients With Obesity

Phase 4

Completed

Conditions: Pregnant Patients With Obesity

Interventions: Drug: High-dose oxytocin
Drug: Low-dose oxytocin

Registration Number: NCT05289869

Lead Sponsor: Ohio State University

Brief Summary: 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.

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: Female

Target Recruitment: 20

Inclusion Criteria

Nulliparity
Maternal age >18 years
Gestational age ≥37w0d
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.
Singleton gestation
Cephalic presentation
Indication for oxytocin use in the first stage of labor
No contraindication to labor or vaginal delivery
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
Cervical dilation ≤4 cm at time of initiation of induction

Exclusion Criteria

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
High-dose oxytocin regimen	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.
Low-dose oxytocin regimen	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.

Primary Outcome Measures

Name	Time	Method
Number of Participants Delivered by Cesarean	Until delivery

Secondary Outcome Measures

Name	Time	Method
Incidence of Maternal ICU Admission	From randomization through 6 weeks postpartum
Labor Agentry Score	Assessed within 12-96 hours after delivery	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.
Incidence of Immediate Postpartum Hemorrhage	Within 24 hours of delivery	Defined as \>1000 mL of blood loss within 24 hours of delivery
Maternal Length of Stay	Within 6 weeks of delivery	Duration of hospitalization for delivery
Incidence of Composite Neonatal Morbidity Outcomes	Within 6 weeks of delivery	Apgar score \<5 at 5 min, arterial cord pH \<7.0 or base deficit \>12 mmol/dL, perinatal death
Duration of Time From Start of Induction to Delivery	From start of induction to delivery	Time from start of induction with medication or Foley catheter until delivery
Incidence of Postpartum Maternal Infectious Morbidity	Within 6 weeks following delivery	Defined as a composite outcome of endomyometritis, puerperal sepsis, or surgical site infection as documented in the the clinical record
Incidence of Maternal Blood Transfusion	From randomization through hospital discharge up to 6 weeks portpartum	Defined as need for blood transfusion
Incidence of NICU Admission	Within 6 weeks of delivery
Duration of the First Stage of Labor	From start of induction to delivery	Time from start of labor to complete dilation
Occurrence of Tachysystole	From start of induction to delivery	Defined as more than 5 contractions in 10 minutes averaged over 30 minutes
Incidence of Uterine Rupture	From start of induction to delivery	Defined as a complete disruption of all uterine layers including serosa
Incidence of Clinical Chorioamnionitis	From start of induction thorough delivery	Defined based on clinical diagnosis as documented by the clinical care team
Incidence of Maternal Death	Within 6 weeks of delivery
Neonatal Length of Stay	Within 6 weeks of delivery	Duration of birth hospitalization
Perception of the Labor, Birth, and Postpartum Experience	Assessed within 12-96 hours after delivery	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.