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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
572
Trigger indicated at folicular diameter smaller than standard clinical practice, from 13mm to 16.9mm
Vida Recoletas Sevilla
Seville, Sevilla, Spain
RECRUITINGPregnancy rate
Rate of positive pregnancies over total transfers performed, according to beta-test result
Time frame: From embryo transfer up to 2 weeks later
Implantation rate
Implantation rate, defined as number of gestational sacs per embryos transferred
Time frame: up to 8 weeks of gestational age
Cancelation rate
Number of cancelled embryo transfers per initiated endometrial preparation cycles. Transfer canceling implies end of study.
Time frame: Perioperative/Periprocedural
Miscarriage rate
Number of miscarriages of any type registered after transfer during the study, per total number of transfers performed
Time frame: From embryo transfer to delivery, up to 40 weeks
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