Oxytocin and Fetal Heart Rate Changes

A Randomized Controlled Trial Evaluating the Effect of the Oxytocin Infusion Rate on Fetal Heart Rate Changes and Maternal-Fetal Outcomes During the Initiation of Combined Spinal-Epidural Labor Analgesia

The reported risk of nonreassuring fetal heart trace following neuraxial analgesia is 3-23%. This variability may be due to fluid and oxytocin management prior to and during the initiation of neuraxial analgesia. The study hypothesis is that decreasing the oxytocin infusion rate by 50 % prior to initiation of combined spinal epidural analgesia will cause a reduction in the incidence of adverse fetal heart rate changes.

Study Overview

• Status: Recruiting
• Conditions: Fetal Heart Rate or Rhythm Abnormality Affecting Fetus; Fetal Bradycardia Complicating Labor and Delivery; Fetal Bradycardia During Labor
• Intervention / Treatment: Drug: Half dose Oxytocin

Detailed Description

Oxytocin is used in labor and delivery to increase the frequency of contractions and augment uterine contractile strength, thereby establishing a regular pattern of labor. However, the administration of exogenous oxytocin in the presence of an uncoordinated labor pattern confers a risk for an increase in uterine contraction frequency, resulting in inadequate relaxation periods. This leads to an increase in the basal tone of the uterus, which may lead to a tetanic contraction with the risk of decreased uteroplacental blood flow and fetal hypoxemia. Previous studies investigating low- versus high-dose oxytocin for induction or augmentation of labor have had conflicting results on the effect on fetal heart rate abnormalities. One of the limitations of these studies is that the labor analgesia was not standardized. The combination of low-dose combined spinal epidural analgesia and the high/low dose oxytocin have not been evaluated. One of the proposed mechanisms for nonreassuring fetal heart a tracing after initiation of analgesia is that the pain relief from neuraxial analgesia causes a decrease in catecholamine release by the sympathetic nervous system. The subsequent decrease in the circulating epinephrine concentration contributes to an increase in uterine tone, as epinephrine is a potent tocolytic agent. The increased tone, in turn, leads to a decrease in placental blood flow, and eventually fetal bradycardia. The primary outcome of this study is the incidence of non-reassuring fetal heart rate tracings within the first 60 minutes after the placement of combined spinal epidural analgesia

• Study Type: Interventional
• Enrollment (Estimated): 730
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Unyime Ituk; Phone Number: 319-356-2633; Email: unyime-ituk@uiowa.edu

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52245
      • Recruiting
      • University of Iowa Hospitals and Clinics
      • Contact: Zita A Sibenaller, PhD; Phone Number: 319-356-8878; Email: zita-sibenaller@uiowa.edu
      • Contact: Unyime Ituk, MD; Phone Number: 319-356-2633; Email: unyime-ituk@uiowa.edu
  • Wisconsin
    • Milwaukee, Wisconsin, United States, 53226
      • Not yet recruiting
      • Medical College of Wisconsin
      • Contact: Meredith Albrecht, MD; Email: maaalbrecht@mcw.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 55 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy nulliparous or multiparous women at term (37 > weeks' gestation)
• Singleton pregnancy
• Request for neuraxial analgesia
• Oxytocin used for induction of labor or augmentation of labor per institutional protocols

Exclusion Criteria:

• Use of chronic analgesic medications
• Prior administration of systemic opioid labor analgesia
• Non-vertex presentation
• Contraindication to neuraxial analgesia
• Category 3 fetal heart rate tracing prior to the initiation of combined spinal epidural analgesia

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
No Intervention: Standard Dose Oxytocin; Patients randomized to the standard dose oxytocin will have their oxytocin infusion maintained at the standard of care protocol prior to placement of a combined spinal epidural for labor analgesia
Experimental: Half Dose Oxytocin; Patients randomized to the half dose oxytocin will have their oxytocin infusion reduced by 50 % prior to placement of a combined spinal epidural for labor analgesia.	Drug: Half dose Oxytocin; Patients randomized to the half dose oxytocin group will have the oxytocin infusion reduced to 50 % prior to placement of combined spinal epidural for labor analgesia

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of non-reassuring fetal heart rate tracings	Fetal heart rate tracings will be examined for 30 minutes before and 60 minutes after the initiation of combined spinal epidural analgesia	1.5 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effect of oxytocin dose on duration of 1st and 2nd stage of labor	The effect of the intervention on the duration of labor	24 hours
Mode of delivery	The effect of the intervention on the rate of spontaneous vaginal delivery, instrumental vaginal delivery and cesarean delivery	24 hours

Collaborators and Investigators

• Sponsor: Unyime Ituk
• Investigators: Study Director: Unyime Ituk, University of Iowa

Publications and helpful links

General Publications

• Clarke VT, Smiley RM, Finster M. Uterine hyperactivity after intrathecal injection of fentanyl for analgesia during labor: a cause of fetal bradycardia? Anesthesiology. 1994 Oct;81(4):1083. doi: 10.1097/00000542-199410000-00041. No abstract available.
• Mardirosoff C, Dumont L, Boulvain M, Tramer MR. Fetal bradycardia due to intrathecal opioids for labour analgesia: a systematic review. BJOG. 2002 Mar;109(3):274-81. doi: 10.1111/j.1471-0528.2002.01380.x.
• Abrao KC, Francisco RPV, Miyadahira S, Cicarelli DD, Zugaib M. Elevation of uterine basal tone and fetal heart rate abnormalities after labor analgesia: a randomized controlled trial. Obstet Gynecol. 2009 Jan;113(1):41-47. doi: 10.1097/AOG.0b013e31818f5eb6.
• Satin AJ, Leveno KJ, Sherman ML, Brewster DS, Cunningham FG. High- versus low-dose oxytocin for labor stimulation. Obstet Gynecol. 1992 Jul;80(1):111-6.
• Budden A, Chen LJ, Henry A. High-dose versus low-dose oxytocin infusion regimens for induction of labour at term. Cochrane Database Syst Rev. 2014 Oct 9;2014(10):CD009701. doi: 10.1002/14651858.CD009701.pub2.

Study record dates

Study Major Dates

• Study Start (Actual): February 20, 2019
• Primary Completion (Estimated): December 31, 2025
• Study Completion (Estimated): December 31, 2025

Study Registration Dates

• First Submitted: July 25, 2017
• First Submitted That Met QC Criteria: July 25, 2017
• First Posted (Actual): July 28, 2017

Study Record Updates

• Last Update Posted (Actual): June 4, 2025
• Last Update Submitted That Met QC Criteria: May 30, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Bradycardia; Physiological Effects of Drugs; Reproductive Control Agents; Oxytocics; Oxytocin
• Other Study ID Numbers: 201609722

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All of the individual participant data collected during the trial, after de-identification will be shared with researchers who provide a methodologically sound proposal, to achieve aims in the approved proposal. IPD will be available for sharing immediately after publication and ending 5 years following article publication.
• IPD Sharing Time Frame: IPD will be available for sharing immediately after publication and ending 5 years following article publication.
• IPD Sharing Access Criteria: IPD will be accessible to researchers who provide a methodologically sound proposal, to achieve aims in the approved proposal
• IPD Sharing Supporting Information Type: CSR

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.: No