Actively Recruiting
Triggering Ovulation at Follicle Size Smaller or Larger Than 17mm in a Modified Natural Cycle
Led by Vida Recoletas Sevilla · Updated on 2026-01-13
572
Participants Needed
1
Research Sites
43 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are studying the timing of ovulation triggering during frozen embryo transfer (FET) in assisted reproductive technology (ART). The trial compares triggering ovulation at smaller follicle sizes (13-16.9mm) with the conventional larger sizes (17-22mm) in a modified natural cycle (mNC). This study aims to improve scheduling flexibility, optimize treatment protocols, and enhance patient care in fertility clinics. Participants are randomly assigned to one of two groups: the control group, where ovulation is triggered at the standard follicle size of at least 17mm, and the experimental group, with triggering at smaller follicle sizes between 13mm and 16.9mm. The study evaluates whether earlier triggering is not worse than the conventional approach in terms of reproductive outcomes. During the study, participants undergo frozen embryo transfer cycles using the assigned ovulation trigger timing. Researchers will measure pregnancy rates up to two weeks after embryo transfer, implantation rates up to eight weeks of gestation, cancellation rates during the procedure, and miscarriage rates up to delivery. The study period extends through these assessments to gather comprehensive data on outcomes and safety.
CONDITIONS
Brief Title
Triggering Ovulation at Follicle Size Smaller or Larger Than 17mm in a Modified Natural Cycle
Who Can Participate
Eligibility Criteria
You may qualify if you...
- At least one expanded blastocyst (regardless of its quality)
- Spontaneous menstrual cycles
- Consent to undergo frozen embryo transfer in a modified natural cycle
You will not qualify if you...
- Abnormal uterine cavity
- Fluid in endometrial cavity
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - 1 menstrual cycle
Participants undergo ovulation triggering at either a smaller follicle size than standard clinical practice or at the standard size during a modified natural cycle.
1 to 2 visits depending on follicle monitoring
Duration - Up to 40 weeks
Participants are monitored for pregnancy outcomes including implantation, miscarriage, and pregnancy rate up to delivery.
Approximately 4 to 6 visits during pregnancy monitoring
Trial Site Locations
Total: 1 location
1
Vida Recoletas Sevilla
Seville, Sevilla, Spain, 41092
Actively Recruiting
Research Team
M
Manuel Fernández Sánchez, MD PhD
C
Clara Palacio de Marco, MSc
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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