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Study on Subfertility: Comparing Estradiol Valerate and Micronised Progesterone for Frozen-Thawed Embryo Transfer in Women Seeking Pregnancy

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying subfertility, which is a condition where individuals have difficulty conceiving. The study aims to find the best way to prepare the lining of the uterus, known as the endometrium, for the transfer of a frozen-thawed embryo. This process is part of assisted reproductive technology, often used by those experiencing challenges with natural conception.

Participants in the study will receive one of two treatments. One group will follow a natural cycle, while the other group will receive an artificial cycle using medications. The medications involved in the artificial cycle include Progynova, which contains estradiol valerate, and Utrogestan, which contains progesterone, micronised. Progynova is taken orally as a coated tablet, and Utrogestan is used as a soft vaginal capsule. These medications help prepare the uterus for embryo transfer.

The study will compare the outcomes of these two approaches over a period of up to 12 months. Participants will be monitored for various outcomes, including the rate of clinical pregnancy, which is confirmed by detecting a fetal heartbeat. Other factors such as biochemical pregnancy rates, miscarriage rates, and live birth rates will also be observed. The study will help determine which method is more effective in supporting successful pregnancies for individuals undergoing frozen-thawed embryo transfers.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm eligibility. This includes verifying age, ovulatory cycle regularity, and uterine cavity condition.

    Eligibility criteria include being a woman aged 18-45, undergoing frozen-thawed embryo transfer (FET) after a first, second, or third fresh IVF/ICSI cycle, and having a natural ovulatory cycle lasting 24-35 days.

  2. Step 2

    Medication administration

    The trial involves the administration of two medications: Progynova and Utrogestan.

    Progynova is taken orally in the form of a 2 mg coated tablet. The dosage and frequency are determined by the study protocol.

    Utrogestan is administered vaginally as a 200 mg soft capsule. The dosage and frequency are also specified by the study protocol.

  3. Step 3

    Embryo transfer

    The embryo transfer process involves either a single embryo transfer (SET) or a double embryo transfer (DET), depending on the study group assignment.

    The transfer is conducted after the endometrial preparation phase, which is optimized according to the study's objective.

  4. Step 4

    Monitoring and follow-up

    Regular monitoring is conducted to assess the endometrial thickness and pattern, as well as to track the progress of the embryo transfer cycle.

    The primary endpoint is the clinical pregnancy rate with a fetal heartbeat. Secondary endpoints include biochemical pregnancy rate, miscarriage rate, and other pregnancy-related outcomes.

  5. Step 5

    Completion and evaluation

    The trial is estimated to conclude by January 1, 2026. Upon completion, data on pregnancy outcomes and patient satisfaction are evaluated.

    The study aims to determine the optimal protocol for endometrial preparation in frozen-thawed embryo transfers.

Who can join the trial?

6 criteria

  • Women who are having a **Frozen Embryo Transfer (FET)** after their first, second, or third fresh **In Vitro Fertilization (IVF)** or **Intracytoplasmic Sperm Injection (ICSI)** cycle. These are methods used to help with pregnancy.
  • Women who will have either a **Single Embryo Transfer (SET)** or a **Double Embryo Transfer (DET)**. This means transferring one or two embryos to the uterus.
  • Women aged between 18 and 45 years old.
  • Women who have a natural **ovulatory cycle** lasting between 24 and 35 days. This means their body naturally releases an egg each month.
  • Women with a normal **uterine cavity**, which is the space inside the uterus. The cavity should have a **fundal indentation** of less than 10mm. This is a small dip at the top of the uterus.
  • Women who have given their written informed consent, meaning they agree to participate in the study after understanding what it involves.

Who cannot join the trial?

4 criteria

  • Individuals who are not experiencing subfertility, which means having difficulty getting pregnant.
  • Individuals who are not within the specified age range for the study.
  • Individuals who are not female, as the study is only for female participants.
  • Individuals who belong to a vulnerable population, which means groups that may need special protection or care.
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Investigated drugs

  • Frozen-thawed embryo transfer in a natural cycle

    This therapy involves transferring an embryo that has been previously frozen and then thawed into the uterus during a woman's natural menstrual cycle. The goal is to allow the embryo to implant and develop naturally, without the use of additional hormonal medications to prepare the uterus.

  • Frozen-thawed embryo transfer in an artificial cycle

    In this therapy, the transfer of a frozen-thawed embryo is done after preparing the uterus with hormonal medications. These medications are used to mimic the natural menstrual cycle and create an optimal environment for the embryo to implant and grow.

What is already known about the treatment

Estradiol – Estradiol is administered orally or through a transdermal patch and is used in the preparation of the endometrium for embryo transfer in assisted reproductive technologies. It is currently well-documented in medical literature as a key component in fertility treatments. The main therapeutic indication is to support the lining of the uterus, making it receptive for embryo implantation. At the molecular level, estradiol works by binding to estrogen receptors, promoting the growth and maintenance of the endometrial lining. It is classified pharmacologically as an estrogen hormone.

Investigated diseases

Subfertility – Subfertility is a condition where a couple experiences difficulty in achieving pregnancy despite having regular, unprotected intercourse for a year or longer. It is not the same as infertility, as subfertility implies a reduced chance of conceiving naturally, but not an impossibility. The condition can be due to various factors affecting either partner, such as hormonal imbalances, issues with sperm or egg quality, or anatomical problems. Subfertility can lead to emotional stress and may require medical intervention to assist in conception. The progression of subfertility varies widely among individuals, with some couples eventually conceiving naturally, while others may need assisted reproductive technologies.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-511890-30-03Estimated enrolment554 patientsSponsorUZ Leuven

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