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Natural Frozen Embryo Transfer (FET) vs Substituted Frozen Embryo Transfer (FET)

Embryo Transfer in Natural vs Substituted Cycle and the Scheduling Pattern of IVF

Status
Completed
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT06053827
Enrollment
1207
Registered
2023-09-26
Start date
2023-09-19
Completion date
2024-07-18
Last updated
2025-12-09

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Fertility Disorders

Brief summary

In frozen embryo transfer substituted cycles, patients are treated with progesterone and estrogen in an attempt to mimic the natural cycle and a transfer is planned whenever the endometrium is ready. In contrast, in frozen embryo transfer natural cycle patients are not taking any hormones, only triggered with hCG (human chorionic gonadotropin) when a dominant follicle is ready or they wait for the disappearance of the dominant follicle to plan the transfer date. Some doctors and centres shift towards using the substituted protocol in an attempt to make scheduling easier with less frequent ultrasounds. This study will aim to compare clinical and biochemical pregnancy rates in patients who underwent frozen embryo transfers in natural cycles vs substituted cycles at the centre.

Interventions

OTHERFrozen embryo transfer

A frozen embryo transfer involves thawing a fertilized embryo and transferring it in the uterus in order to obtain a pregnancy

Sponsors

Clinique Ovo
Lead SponsorINDUSTRY

Study design

Observational model
COHORT
Time perspective
RETROSPECTIVE

Eligibility

Sex/Gender
FEMALE
Age
No minimum to 40 Years

Inclusion criteria

* Age \< 40 years old * Women having undergone either a frozen embryo transfer in natural cycle or substituted cycle * IVF and FET cycles done at Clinique OVO

Exclusion criteria

* egg or embryo recipient * History of recurrent miscarriages, defined as ≥ 3 consecutive losses * Patients that needed Viagra, Plasma-Rich Platelet (PRP) or other modalities to improve their endometrial thickness * Uterine abnormalities * Abnormal hormonal profiles * FET Stimulated cycles * History of recurrent implantation failure defined as failed ≥ 2 euploid embryos transfer or ≥ 3 blastocysts

Design outcomes

Primary

MeasureTime frameDescription
Evaluate the clinical pregnancy rate of embryo transfer in natural vs substituted cycles6 to 8 weeks after Frozen Embryo Transferclinical pregnancy is the presence of fetal heartbeat at the viability ultrasound

Countries

Canada

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 6, 2026