Can Labor Pain be Reduced by Open Placebo Intervention? A Bayesian Account for Labor Pain

NCT07077590 | Not Yet Recruiting

• 1 other identifier: HINC-0091-24
• Study Type: interventional
• Target: 120
• Locations: 1 country
• Sites: 1

Brief Summary

The human nervous system continuously processes a potentially overwhelming stream of signals from bodily senses, which induces uncertainty. To reduce this uncertainty, the brain transforms sensory input into a reliable perception of the world. According to the Bayesian hypothesis of perception, based on probabilistic estimation, conscious perception is shaped by both the current state of sensory information and by past experiences, associative learning, stored memories, and beliefs. This framework is particularly relevant for explaining the phenomenon of pain, including individual differences in pain perception and response. The focus of the present work is pain during childbirth, representing a major acute pain event. Pain during childbirth is a complex and unique experience with both sensory and emotional components, embedded within a defined physiological process. A key concept of the Bayesian model related to pain perception is the placebo phenomenon, which offers a compelling explanation for the analgesic placebo response. The overarching aim of this study is to evaluate whether the Bayesian model can account for changes in pain perception during labor following open placebo administration, as well as the involvement of expectations and personality traits. The study will be conducted at Hillel-Yaffe Medical Center, with the participation of 120 pregnant women. The research will be divided into two stages. The first stage will occur during the prenatal period, while participants are in a pain-free state. During this stage, questionnaires will be completed to assess expectations and personality traits, and the Focused Analgesia Selection Test (FAST) will be administered to evaluate within-subject variability in pain intensity. The second stage will take place during labor and will involve an open placebo intervention, during which pain levels and analgesic consumption will be monitored.

Conditions

Labor Pain and to Reduce Pain

Keywords

Labor pain; Open placebo; Within-subjects variability; personality

Outcome Measures

Primary Outcomes (2)

• Pain intensity on a 0-10 Numerical Pain Scale (NPS)

  Pain assessment will be performed by using the unidimensional Numerical Pain Scale (NPS) by asking the patient to range the pain, subjectively, from her point of view, from none (0) to a worst imaginable pain (10). Pain intensity will be assessed once in 60 minutes for the duration of the labor. Since each labor duration is difrent, the primary outcome would be the levels of pain during the labor process. Those intensities over time will be compared bewteen the two study arms. In addition, in additional analyses, pain intensities will be compared for each labor phase, seperatly.

  Each 60 minutes through the labor process.

• Within-subject variability of pain reports

  The Focused Analgesia Selection Test (FAST) procedure will be used to assess the within-subject variability of pain reports. The FAST includes exposure to several thermal noxious stimuli, administrated repeatedly at different intensities, which will be delivered to the ventral surface of the non-dominant arm (Medoc® Thermal Sensory Analyzer II with a thermodin size of 30 \* 30 mm). Pain intensity ratings are obtained from the participant after each stimulus on a 0-100 numerical rating scale (NRS) ranging from 0 ("no pain") to 100 ("worst pain imaginable"). Stimuli will be triggered automatically every 20 seconds. Relationship between stimulus intensities and pain reports are calculated (R2 and ICC) to assess the magnitude of variability observed.

  At baseline

Secondary Outcomes (8)

• Assessment of expectations from the treatment

  At baseline

• Fear of childbirth

  At baseline

• Suggestibility

  At baseline

• Anxiety

  At baseline

• Interoception

  At baseline

Study Arms (2)

Usual care (control arm)

NO INTERVENTION

Any woman who arrive to the labor room is connected to fluids (Hartman's solution), as part of routine care. In the control arm, the information given will be:" These fluids are important to keep your fluids balance, and is given to any delivering woman".

Open placebo

ACTIVE COMPARATOR

Any woman who arrive to the labor room is connected to fluids (Hartman's solution), as part of routine care. The study intervention (open placebo) is based on injection of placebo into an infusion bag accompanied by the verbal explanation. The placebo is 5 ml NaCl 0.9%.

Behavioral: Open Label Placebo

Interventions

Open Label Placebo BEHAVIORAL

Any woman who arrive to the labor room is connected to fluids (Hartman's solution), as part of routine care. The study intervention (open placebo) is based on injection of placebo into an infusion bag accompanied by a verbal suggustion. The placebo is 5 ml NaCl 0.9%.

Open placebo

Eligibility Criteria

• Age: 18 Years+
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Pregnant women with one fetus who are after 24th week onwards.
• Without contraindications for analgesia at birth.
• Without contraindications for vaginal birth.

You may not qualify if:

• Women in obstetric emergencies, including intrauterine death, suspected placental separation, uterine rupture, placental opening
• Elective cesarean section
• Receiving psychiatric treatment.

Sponsors & Collaborators

• Roi Treister: lead
• Hillel Yaffe Medical Center: collaborator

Study Sites (1)

Hillel Yaffe Medical Center

Hadera, 3820302, Israel

Location

MeSH Terms

Conditions

Labor Pain

Condition Hierarchy (Ancestors)

Pain; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Ira Linetsky, RN, MA

CONTACT

+972-504905205; iral77@walla.co.il

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Prof. Roi Treister, PhD

Study Record Dates

• First Submitted: May 7, 2025
• First Posted: July 22, 2025
• Study Start: July 15, 2025
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): December 31, 2027
• Last Updated: July 22, 2025

Record last verified: 2025-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, CSR
• Time Frame: After publication of results
• Access Criteria: Everyone

Locations

IL (1)