Comparison of Pregnancy Rates in Modified Natural Frozen Embryo Transfer (FET) Cycle After Luteal Support with GnRH Agonist Versus Progesterone

What Was Tested

The trial (early phase 1) is built around Nafarelin.

Endogenous progesterone from the corpus luteum, following frozen embryo transfer in natural or modified natural cycles, is expected to provide sufficient luteal support, as observed in spontaneous pregnancies.

It had two arms (groups): SYNAREL (active comparator) and UTEROGESTAN (active comparator).

The registry classes the interventions as drug.

More on the Plan

Background: The ability to transfer frozen embryos allows for the storage of embryos created during in vitro fertilization (IVF) treatments for later use.

There are several methods for preparing the endometrium for frozen embryo transfer: 1.

Natural Cycle (NC) - Timing ovulation by detecting the LH surge.

However, its disadvantages include the need for close monitoring to detect ovulation and the inflexibility of embryo transfer timing, leading to a higher rate of cycle cancellations. 2.

Who Took Part

150 planned participants were the target.

It was open to women only aged from 18 years up to 40 years.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: Women undergoing frozen embryo transfer in a modified natural cycle.

The full record lists 5 inclusion and 8 exclusion criteria; among the exclusions: women undergoing medicated fet cycles; BMI \>35 or \<18; women with hydrosalpinx.

How the Study Was Run

It was run as a randomized, parallel-group and open-label study.

Random assignment meant chance, not the researchers, decided who got Nafarelin and who got the comparison, which limits bias.

The Nafarelin group and the comparison group ran side by side rather than switching.

Nothing was hidden in this open-label Nafarelin study: the participants and staff both knew the treatment.

It started in 2025-03 with completion listed for 2027-03.

Its stated primary purpose is treatment.

What Was Measured

Researchers chose this as the main measure: clinical pregnancy rate (time frame: two months after ET).

It also tracked 4 secondary outcomes, for example positive pregancny, implantation rate, live birth rate and miscarriage rate.

What This Means in Plain Language

Put simply, this is a early phase 1, randomized trial of Nafarelin in 150 people.

Its status is not yet recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Nafarelin compound page, all human trials.