Diphenhydramine for cervical edema during active labor

Anticholinergics for Cervical Edema in Labor (ACCEL)

Phase2; Phase3 Interventional The University of Texas Health Science Center, Houston · NCT06702670

This will test whether a single IV dose of diphenhydramine given during active labor can prevent labor arrest and lower cesarean delivery rates in first-time (primiparous) women.

Quick facts

PhasePhase2; Phase3
Study typeInterventional
Enrollment200 (estimated)
Ages18 Years and up
SexFemale
SponsorThe University of Texas Health Science Center, Houston Academic / other
Locations1 site (Houston, Texas)
Trial IDNCT06702670 on ClinicalTrials.gov

What this trial studies

This Phase 2/3 interventional study gives a single intravenous dose of diphenhydramine to primiparous women in active labor and compares outcomes to usual care. Eligible participants are ≥34 weeks with a viable singleton pregnancy, ruptured membranes, a Category I fetal tracing, and cervical dilation ≥6 cm; those with Category II/III tracings or an allergy to diphenhydramine are excluded. The primary goal is to see if treating presumed cervical edema with an anticholinergic reduces labor arrest and cesarean deliveries. Treatment is administered in the hospital labor ward at UTHealth Houston and delivery outcomes are followed through birth.

Who should consider this trial

Good fit: First-time pregnant women (primiparous) at or beyond 34 weeks with a ruptured membrane, a viable singleton fetus, active labor (≥6 cm dilation), and a reassuring (Category I) fetal heart tracing.

Not a fit: Women with nonreassuring fetal tracings (Category II/III), a known allergy to diphenhydramine, multiple gestation, or those not in active labor are unlikely to receive benefit from this intervention.

Why it matters

Potential benefit: If effective, a single inexpensive IV dose could reduce the chance of labor arrest and decrease cesarean deliveries for first-time mothers.

How similar studies have performed: Using anticholinergic or antihistamine drugs for cervical edema in labor is a relatively novel approach with limited prior clinical evidence supporting its effectiveness.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Primiparous
* Viable single intrauterine pregnancy

  -≥ 34 weeks of gestation
* Ruptured membranes
* Category I tracing at time of inclusion
* Active phase of labor (\>=6 cm of cervix dilation)

Exclusion Criteria:

* Category II or III tracing
* Allergy to the study medication (IV Diphenhydramine)

Where this trial is running

Houston, Texas

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Labor Dystociadilationlabor
Last reviewed 2026-06-09 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.