Relaxin Measurement in Different Endometrial Preparation Approaches for Frozen Embryo Transfer

May 6, 2026 updated by: ART Fertility Clinics LLC
To investigate the levels of Relaxin in different types of endometrial preparation for a frozen embryo transfer cycle. Up to now it is unclear, whether ovulation with a functional corpus luteum (CL) will be present in a natural proliferative phase (NPP) endometrial preparation approach.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The last years have seen a distinct shift from fresh (fresh ET) to frozen embryo transfer (FET) cycles. Furthermore it became obvious, that the endometrial preparation approach has a significant impact on the course of the pregnancy and that a HRT endometrial preparation approach is associated with a higher risk for bleeding and miscarriages in early pregnancy and for the development of pregnancy induced hypertension and pre-eclampsia later in pregnancy.

These conditions are attributed to the absence of a CL in the HRT approach. Lately a new endometrial preparation approach is discussed and performed, the so called natural proliferative phase protocol, in which the follicle growth is monitored and when the lining is deemed to have a sufficient thickness and the triple lining pattern, exogeneous progesterone is started to induce secretory transformation before spontaneous ovulation. Despite some studies showing, that exogeneous progesterone administration might induce ovulation, it is not clear whether there will be a CL, producing Relaxin, in the NPP approach.

Study Type

Observational

Enrollment (Estimated)

5

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

- healthy volunteers with regular cycles

Description

Inclusion Criteria:

  • regular menstrual cycles

Exclusion Criteria:

  • abnormal findings of the ovaries (e.g endometriosis)
  • Intake of any hormones within 3 months of study start
  • desire to become pregnant

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Natural cycle
Monitoring of a natural cycle
natural proliferative phase cycle
Monitoring of a natural proliferative phase cycle
Drug: Exposure to progesterone or HRT medication
to add either progesterone only in the NPP protocol or E2 and progesterone in a HRT protocol
Hormonal replacement cycle
Monitoring of a hormonal replacement cycle
Drug: Exposure to progesterone or HRT medication
to add either progesterone only in the NPP protocol or E2 and progesterone in a HRT protocol

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Relaxin measurement
Time Frame: 4 to 6 months
Measurement of Relaxin in the different types of frozen embryo transfer
4 to 6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

ART Fertility Clinics LLC

Investigators

  • Principal Investigator: Barbara Lawrenz, PhD, ART Fertility Clinic

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 1, 2024

Primary Completion (Estimated)

December 31, 2026

Study Completion (Estimated)

December 31, 2026

Study Registration Dates

First Submitted

July 25, 2024

First Submitted That Met QC Criteria

July 25, 2024

First Posted (Actual)

July 29, 2024

Study Record Updates

Last Update Posted (Actual)

May 11, 2026

Last Update Submitted That Met QC Criteria

May 6, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2406-ABU-007-BL

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

on request

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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