Recovery Rate From Category II to Category I EFM Tracings in Pregnant Women Receiving Bolus vs Continuous Intravenous Fluid Administration (IUR-RCT)

Recovery Rate From Category II to Category I Electronic Fetal Monitoring (EFM) Tracings in Pregnant Women Receiving Bolus vs Continuous Intravenous Fluid Administration: A Randomized Controlled Trial

The goal of this clinical trial is to learn which method of intravenous fluid works better for treating abnormal fetal heart rate patterns during labour in low-risk pregnant women at term. The main question it aims to answer is:

Does a rapid fluid bolus (500 mL given quickly) convert abnormal fetal heart rate tracings to normal within 30 minutes better than slow continuous infusion? Researchers will compare a 500 mL normal saline bolus followed by continuous infusion to continuous infusion alone to see which method improves fetal heart rate patterns faster.

Participants will:

• Be placed in the left lateral position and receive supplemental oxygen by face mask
• Have oxytocin stopped if it is being given
• Receive normal saline through an IV line - either as a rapid bolus or a slow continuous drip, depending on which group they are assigned to
• Have fetal heart rate monitored continuously and assessed at 30, 60, and 120 minutes
• Have blood pressure, heart rate, and oxygen levels checked every 15 minutes
• Have two ultrasound measurements taken - one of a vein in the abdomen and one of blood flow in the umbilical cord - at the start and at 30 minutes

Study Overview

• Status: Completed
• Conditions: Fetal Non Reassuring
• Intervention / Treatment: Drug: 500 mL normal saline rapid bolus followed by remaining volume at 150 mL/hour

Detailed Description

Intravenous fluid is a key component of intrauterine resuscitation (IUR) for Category II fetal heart rate tracings. However, no randomised trial has compared bolus versus continuous infusion directly.

Intervention :

Both groups receive normal saline from a 1000 mL bag through a 21-gauge cannula. The bolus group receives the first 500 mL as a rapid free-flow infusion (IV bag positioned 110 cm above hand level), followed by the remaining 500 mL at 150 mL/h. The continuous group receives the full 1000 mL at 150 mL/h throughout. All participants also receive standard IUR: left lateral positioning, oxytocin discontinuation where applicable, and supplemental oxygen 10 L/min by face mask.

Outcome Assessment :

The primary outcome (EFM category at 30 minutes) is assessed by the attending physician from a separate room, blinded to group allocation. All EFM tracings are also independently re-adjudicated by two blinded reviewers after delivery.

Physiological Surrogates :

A single trained operator measures inferior vena cava collapsibility index (IVC-CI) by M-mode ultrasound and umbilical artery Doppler pulsatility index (UA PI) at baseline and 30 minutes to assess maternal volume status and fetoplacental resistance.

Statistical Analysis :

The primary analysis uses Fisher's exact test with risk difference, relative risk, and number needed to treat. Cumulative recovery is modelled by discrete-time survival analysis. A pre-specified BMI subgroup analysis and blinded re-adjudication sensitivity analysis are included.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Thailand
  • Changwat Chon Buri
    • Si Racha, Changwat Chon Buri, Thailand, 20110
      • Queen Savang Vadhana Memorial Hospital, Chon Buri, Chon Buri 20110 Recruiting

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Singleton
2. Thai nationality
3. Gestational Age more than equal 37 Weeks
4. Maternal Age 20-35 Years
5. Cephalic Presentation
6. Electronic Fetal Monitoring (EFM) Category II

Exclusion Criteria:

1. Maternal underlying diseases : Cardiac disease, Pulmonary disease), Overt DM, Thyroid disease,. etc
2. High risk pregnancy :Pre-eclampsia/Eclampsia), GDM
3. Fetal abnormalities
4. Maternal receiving medications for example : Magnesium sulfate, Pethidine, Opioids
5. Oligohydramnios

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group B (Continuous infusion group): Receives 1,000 mL of normal saline at 150 mL/hour; Group B (Continuous infusion group): Receives 1,000 mL of normal saline at 150 mL/hour without a preceding bolus	Drug: 500 mL normal saline rapid bolus followed by remaining volume at 150 mL/hour; Participants receive 500 mL of normal saline as a rapid free-flow intravenous bolus through a 21-gauge cannula, with the IV bag positioned 110 cm above hand level. Once 500 mL is delivered, the remaining 500 mL from the same bag is continued at 150 mL/h. All infusions are continued until delivery or clinical decision to discontinue.
Experimental: Group A (Bolus group): Receives 500 mL of normal saline intravenously as a bolus; Receives 500 mL of normal saline intravenously as a bolus, followed by 1,000 mL normal saline at 150 mL/hour	Drug: 500 mL normal saline rapid bolus followed by remaining volume at 150 mL/hour; Participants receive 500 mL of normal saline as a rapid free-flow intravenous bolus through a 21-gauge cannula, with the IV bag positioned 110 cm above hand level. Once 500 mL is delivered, the remaining 500 mL from the same bag is continued at 150 mL/h. All infusions are continued until delivery or clinical decision to discontinue.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recovery rate from Category II to Category I EFM tracing at 30 minutes	Proportion of participants with conversion from Category II to Category I electronic fetal monitoring (EFM) tracing within 30 minutes of intervention initiation, classified using the NICHD three-tier system. Recovery is defined as conversion to Category I. Non-recovery is defined as persistence of Category II or progression to Category III at 30 minutes. Classification is performed by the attending physician by real-time bedside assessment.	30 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recovery rate from Category II to Category I EFM tracing at 60 minutes	Proportion of participants with conversion from Category II to Category I EFM tracing within 60 minutes of intervention initiation, using the same NICHD classification. Time Frame:	60 minutes
Recovery rate from Category II to Category I EFM tracing at 120 minutes	Proportion of participants with conversion from Category II to Category I EFM tracing within 120 minutes of intervention initiation.	120 minutes
Mode of delivery	Route of delivery classified as vaginal delivery or caesarean section.	At delivery
Neonatal Intensive Care Unit (NICU) admission	Proportion of neonates admitted to the neonatal intensive care unit following delivery.	Within 24 hours of delivery
Apgar score at 1 minute	Proportion of neonates with 1-minute Apgar score below 7	1 minute after delivery
Apgar score at 5 minutes	Proportion of neonates with 5-minute Apgar score below 7	5 minutes after delivery

Collaborators and Investigators

• Sponsor: Queen Savang Vadhana Memorial Hospital, Thailand

Publications and helpful links

General Publications

• 1. World Health Organization. WHO statement on caesarean section rates. WHO/RHR/15.02. Geneva: World Health Organization; 2015. 2. Royal Thai College of Obstetricians Gynaecologists. Position Statement on Caesarean Section (Revised Edition 2023). Bangkok: RTCOG; 2023. 3. Freeman RK, Garite TJ, Nageotte MP, Miller LA. Fetal Heart Rate Monitoring. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2012. 4. Abati I, Micaglio M, Giugni D, Seravalli V, Vannucci G, Di Tommaso M. Maternal oxygen administration during labor: a controversial practice. Children. 2023;10(8):1420. 5. Kearney L, Craswell A, Dick N, Massey D, Nugent R. Evidence-based guidelines for intrapartum maternal hydration assessment and management: a scoping review. Birth. 2024;51(2):253-63. 6. Simpson KR, James DC. Efficacy of intrauterine resuscitation techniques in improving fetal oxygen status during labor. Obstetrics & Gynecology. 2005;105(6):1362-8. 7. Reddy UM, Weiner SJ, Saade GR, Varner MW, Blackwell SC, Thorp JM, Jr. Intrapartum resuscitation interventions for category II fetal heart rate tracings and improvement to category I. Obstetrics & Gynecology. 2021;138(3):409-16. 8. American College of Obstetrician Gynecologists. Practice Bulletin No. 116: Management of intrapartum fetal heart rate tracings. Obstetrics & Gynecology. 2010;116(5):1232-40. 9. Kitsricharoenchai A, Sunsaneevithayakul P, Boriboonhirunsarn D. Success rate of intrauterine fetal resuscitation in NICHD category II abnormal fetal heart rate pattern. Thai Journal of Obstetrics and Gynaecology. 2021;29(3):159-68. 10. Hopewell S, Chan A-W, Collins GS, Hróbjartsson A, Moher D, Schulz KF, et al. CONSORT 2025 statement: updated guideline for reporting randomised trials. BMJ. 2025;389:e081123. 11. Hoffmann TC, Glasziou PP, Boutron I, Milne R, Perera R, Moher D, et al. Better reporting of interventions: template for intervention description and replication (TIDieR) checklist and guide. BMJ. 2014;348:g1687. 12. Manyara AM, Davies P, Stewa

Study record dates

Study Major Dates

• Study Start (Actual): December 10, 2025
• Primary Completion (Actual): March 27, 2026
• Study Completion (Actual): March 31, 2026

Study Registration Dates

• First Submitted: November 20, 2025
• First Submitted That Met QC Criteria: November 20, 2025
• First Posted (Actual): December 3, 2025

Study Record Updates

• Last Update Posted (Actual): June 10, 2026
• Last Update Submitted That Met QC Criteria: June 7, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Bolus fluid administration, Non-reassuring fetal status, Fetal distress, Intrauterine resuscitation
• Additional Relevant MeSH Terms: Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Fetal Distress
• Other Study ID Numbers: 013/2568

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Data was saved in form of Microsoft excel spreadsheet and SPSS file

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No