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Assessing the Convenience of Natural Proliferative Phase Frozen Embryo Transfer

Assessing the Convenience of Natural Proliferative Phase Frozen Embryo Transfer: an Ambispective Cohort Study

Status
Recruiting
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT06307184
Enrollment
530
Registered
2024-03-12
Start date
2024-02-23
Completion date
2026-12-01
Last updated
2026-02-23

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

Conditions

Frozen Embryo Transfer

Keywords

Endometrial preparation, Natural cycle, Progesterone, Pregnancy

Brief summary

This study will assess the convenience of the natural proliferative phase frozen embryo transfer (NPP-FET) in terms of number of number of appointments needed before cycle scheduling.

Detailed description

Frozen embryo transfer (FET) is increasingly used nowadays in Assisted Reproductive Techniques (ART) clinics. Several factors account for this uprising. Among them, the concept of ovarian hyperstimulation syndrome (OHSS)-free clinic, the increasing use of preimplantation genetic testing (PGT), the improved vitrification systems, and the growing evidence regarding similar, or even better, pregnancy rates when FET are compared to fresh embryo transfers. In the last few years, research has focused on the selection of the best protocol for endometrial preparation in patients undergoing FET cycles. Despite the accumulating evidence suggesting similar reproductive outcomes following both artificial cycle (AC-FET) and natural cycle (NC-FET) protocols, AC-FET is frequently adopted in ART centers due to its convenience in terms of cycle scheduling. However, a role for the corpus luteum in the maternal vasodilatory changes of early pregnancy has recently been associated with a decreased risk of pre-eclampsia. In fact, several large cohort studies have reported a higher risk of hypertensive diseases of pregnancy, macrosomia, post-term delivery and cesarean section following AC-FET. The NPP-FET protocol is a strategy that potentially allows for cycle scheduling while maintaining the benefits of the natural cycle in terms of pregnancy outcomes. The main goal of the present study is to analyze its convenience in terms of the number of appointments needed before FET scheduling by comparing it with the NC-FET protocol. Additionally, the investigators aim to compare the reproductive outcomes between the two strategies and to analyze whether NPP-FET patients undergo ovulation. Briefly, the study group will prospectively recruit ovulatory patients who will perform vaginal ultrasound monitoring will be performed on cycle day 8-12, depending on the length of the patients' menstrual cycle. When the endometrial thickness is at least 7 mm and the dominant follicle is at least 13 mm, vaginal micronized progesterone will be initiated at 400mg every 12 hours. One embryo will be transferred on the fifth day of progesterone supplementation under ultrasound guidance. The control group will include a retrospective cohort of ovulatory patients who underwent NC-FET.

Interventions

PROCEDURENatural proliferative phase frozen embryo transfer

When endometrial thickness is above 7 mm, vaginal micronized progesterone will be administered 400mg 12/12h when the dominant follicle is at least 13 mm, serum estradiol (E2) levels are \>80 pg/ml, and serum progesterone levels are \<1.5ng/ml. Embryo transfer will be performed on the fifth day of progesterone.

Sponsors

Instituto Valenciano de Infertilidade de Lisboa
Lead SponsorNETWORK
Gedeon Richter Ltd.
CollaboratorINDUSTRY

Study design

Observational model
COHORT
Time perspective
OTHER

Eligibility

Sex/Gender
FEMALE
Age
18 Years to 49 Years
Healthy volunteers
No

Inclusion criteria

* Endometrial thickness ≥ 7 mm on the day of starting progesterone-based luteal phase support (LPS) * Serum progesterone levels \<1.5 ng/ml on the day of starting progesterone-based LPS * LPS with micronized progesterone 400mg b.i.d. * Regular cycles (\>24 days, ≤ 38 days) * IVF/ICSI with donated oocytes * Single blastocyst stage embryo transfer * First or second embryo transfer from the same cohort

Exclusion criteria

* Use of exogenous ovarian stimulation during FET * Untreated hydrosalpinx, polyp, submucous myomas or severe adenomyosis * Recurrent pregnancy loss (≥ 3 previous pregnancy losses) * Recurrent implantation failure with embryos from oocyte donation (≥ 3 previous failed embryo transfers) * Personalized initiation of exogenous progesterone according to a previous endometrial receptivity assay test

Design outcomes

Primary

MeasureTime frameDescription
Number of appointments needed before cycle schedulingUp to three weeksNumber of visits for cycle monitoring until embryo transfer scheduling

Secondary

MeasureTime frameDescription
Cycle duration until embryo transfer (days)Up to four weeksNumber of days since the first day of menstrual bleeding until the day of embryo transfer
Proportion of patients with low progesterone values on the day of embryo transferOne dayPercentage of patients with low serum progesterone levels on the day of embryo transfer
Human corionic gonadotropin (hCG) positive rate10-14 days after ETProportion of patients with a positive hCG test
Miscarriage rateUp to 20 weeks after ETProportion of patients with spontaneous loss of an intra-uterine pregnancy prior to 22 completed weeks of gestational age
Ongoing pregnancy rate9-11 weeks after ETProportion of patients with a pregnancy beyond the 11th week
Live birth rate40 weeks after ETProportion of patients with a live birth

Countries

Portugal

Contacts

CONTACTAna R Neves, MD, PhD
ana.neves@ivirma.com218 503 210
PRINCIPAL_INVESTIGATORAna R Neves, MP

Instutito Valenciano de Infertilidade de Lisboa (IVI-RMA Lisboa)

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 24, 2026