Triggering Ovulation at Follicle Size Smaller or Larger Than 17mm in a Modified Natural Cycle

NCT07088952 | Recruiting

• 1 other identifier: 2310-SEV-02-MF
• Study Type: interventional
• Target: 572
• Locations: 1 country
• Sites: 1

Brief Summary

The rise in frozen embryo transfer (FET) cycles within assisted reproductive technology (ART) has sparked the need to refine endometrial preparation protocols. The switch from hormone replacement cycles (HRT) to natural cycles, poses scheduling challenges onto laboratories, doctors and patients. The modified natural cycle (mNC), offering more precision for scheduling, shows promise but lacks comprehensive data on the potential flexibility of triggering criteria that may allow to control timing in a wider range. This prospective randomized study seeks to address this knowledge gap by evaluating the non-inferiority of triggering ovulation in mNC with follicle diameters of 13-16.9mm compared to the conventional 17-22mm. The study aims to enhance the understanding of the impact of follicle size at ovulation in reproductive outcomes, optimize FET treatments providing a more flexible mNC protocol, and improve patient care in ART clinics.

Conditions

Embryo Transfer

Keywords

Natural Cycle; Frozen Embryo Transfer; Follicle Size; Pregnancy; Implantation

Outcome Measures

Primary Outcomes (1)

• Pregnancy rate

  Rate of positive pregnancies over total transfers performed, according to beta-test result

  From embryo transfer up to 2 weeks later

Secondary Outcomes (3)

• Implantation rate

  up to 8 weeks of gestational age

• Cancelation rate

  Perioperative/Periprocedural

• Miscarriage rate

  From embryo transfer to delivery, up to 40 weeks

Study Arms (2)

Control

NO INTERVENTION

Trigger indicated as per standard clinical practice at folicular diameter of at least 17mm

Early trigger

EXPERIMENTAL

Trigger indicated at folicular diameter smaller than standard clinical practice

Procedure: Trigger at smaller folicular size

Interventions

Trigger at smaller folicular size PROCEDURE

Trigger indicated at folicular diameter smaller than standard clinical practice, from 13mm to 16.9mm

Early trigger

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• At least one expanded blastocyst (regardless of its quality)
• Spontaneous menstrual cycles
• Consent to undergo frozen embryo transfer in a modified natural cycle

You may not qualify if:

• Abnormal uterine cavity
• Fluid in endometrial cavity

Sponsors & Collaborators

• Vida Recoletas Sevilla: lead

Study Sites (1)

Vida Recoletas Sevilla

Seville, Sevilla, 41092, Spain

RECRUITING

Central Study Contacts

Manuel Fernández Sánchez, MD PhD

CONTACT

+34954286274; vida.investiga@gruporecoletas.com

Clara Palacio de Marco, MSc

CONTACT

+34954286274; clara.palacio@gruporecoletas.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Prospective open randomized parallel group 1:1 ratio

Study Record Dates

• First Submitted: June 17, 2025
• First Posted: July 28, 2025
• Study Start: October 22, 2025
• Primary Completion (Estimated): July 30, 2027
• Study Completion (Estimated): May 30, 2028
• Last Updated: January 13, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will share

Locations

ES (1)