Actively Recruiting
Assessing the Convenience of Natural Proliferative Phase Frozen Embryo Transfer: an Ambispective Cohort Study
Led by Instituto Valenciano de Infertilidade de Lisboa · Updated on 2026-02-23
530
Participants Needed
1
Research Sites
13 weeks
Total Duration
On this page
Sponsors
I
Instituto Valenciano de Infertilidade de Lisboa
Lead Sponsor
G
Gedeon Richter Ltd.
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating the convenience of the natural proliferative phase frozen embryo transfer (NPP-FET) compared to the natural cycle frozen embryo transfer (NC-FET) in women undergoing assisted reproductive techniques. The study focuses on ovulatory patients and aims to analyze the number of appointments needed before cycle scheduling. It also compares reproductive outcomes between the two protocols and investigates if patients undergoing NPP-FET experience ovulation. This observational study addresses concerns related to pregnancy risks and cycle scheduling in frozen embryo transfer. The NPP-FET group will receive vaginal micronized progesterone at 400 mg every 12 hours once the endometrial thickness is at least 7 mm and the dominant follicle is at least 13 mm, with specific hormone levels confirmed. Embryo transfer occurs on the fifth day of progesterone supplementation, and progesterone continues until the 11th week of pregnancy. The control group includes a retrospective cohort of patients who underwent the NC-FET protocol, with embryo transfer timing based on natural ovulation markers and progesterone use after ovulation or hCG trigger. Participants will undergo vaginal ultrasound monitoring between cycle days 8 to 12 to measure follicle and endometrial thickness. Hormone levels such as estradiol, progesterone, and luteinizing hormone are measured to guide treatment. Researchers will track the number of appointments before scheduling, cycle duration until embryo transfer, hormone levels at transfer, pregnancy rates, miscarriage rates, ongoing pregnancies, and live births. Progesterone use and pregnancy monitoring continue for several weeks post-transfer, with total follow-up lasting up to 40 weeks after embryo transfer.
CONDITIONS
Brief Title
Assessing the Convenience of Natural Proliferative Phase Frozen Embryo Transfer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Endometrial thickness 27 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 twice daily
- Regular menstrual cycles between 24 and 38 days
- IVF or ICSI performed with donated oocytes
- Single blastocyst stage embryo transfer
- First or second embryo transfer from the same cohort
You will not qualify if you...
- Use of exogenous ovarian stimulation during frozen embryo transfer
- Untreated hydrosalpinx, polyp, submucous myomas, or severe adenomyosis
- History of recurrent pregnancy loss (3 or more previous losses)
- Recurrent implantation failure with embryos from oocyte donation (3 or more failed transfers)
- Personalized initiation of exogenous progesterone based on previous endometrial receptivity assay test
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 - Up to 4 weeks
Participants receive vaginal ultrasound monitoring in the proliferative phase to assess endometrial thickness and follicle size. When criteria are met, vaginal micronized progesterone is started and one embryo is transferred on the fifth day of progesterone supplementation. Progesterone is continued until the 11th week of pregnancy.
1 to 3 visits before embryo transfer, plus follow-up visits as pregnancy progresses
Duration - Up to 4 weeks
Participants are monitored for a spontaneous LH peak or receive r-hCG to trigger ovulation. Vaginal micronized progesterone is started accordingly. One embryo is transferred 6 to 7 days after ovulation trigger. Progesterone is continued until the 8th week of pregnancy.
1 to 3 visits before embryo transfer, plus follow-up visits as pregnancy progresses
Trial Site Locations
Total: 1 location
1
Instituto Valenciano de Infertilidade
Lisbon, Portugal
Actively Recruiting
Research Team
A
Ana R Neves, MD, PhD
How is the study designed?
Study Type
OBSERVATIONAL
Masking
N/A
Allocation
N/A
Model
N/A
Primary Purpose
N/A
Number of Arms
2
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