Corpus Luteum Function and Cardiovascular Adaptation in a Natural MOCK Cycle.
CLEAR
1 other identifier
observational
118
1 country
1
Brief Summary
In infertility treatment, embryos are created in vitro after eggs have been fertilised by sperm using in vitro fertilisation or intracytoplasmic sperm injection techniques. These embryos, resulting from hormonal ovarian stimulation, can be transferred shortly after egg retrieval (fresh transfer) or frozen for later use. Both natural menstrual cycles and artificial cycles (using hormones to mimic a normal cycle) can prepare the uterus for embryo transfer. Patients with regular menstrual cycles often prefer the non-medicated approach. However, these cycles offer less flexibility in timing because they rely on ovulation. As the number of FET cycles increases worldwide, scientists are exploring the possibility of inducing ovulation in smaller follicles to increase the flexibility of natural cycles. However, the safety for future pregnancies is unknown. This study aims to better understand the function of the corpus luteum, the follicle remnant in the ovary after ovulation, by measuring several factors that change throughout the cycle due to substances produced by the corpus luteum. The results of the study will have a direct impact on clinical practice by increasing the flexibility of frozen transfer cycles.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P50-P75 for all trials
Started Jul 2026
Typical duration for all trials
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
June 9, 2026
CompletedFirst Posted
Study publicly available on registry
June 15, 2026
CompletedStudy Start
First participant enrolled
July 1, 2026
ExpectedPrimary Completion
Last participant's last visit for primary outcome
February 1, 2028
Study Completion
Last participant's last visit for all outcomes
September 1, 2028
June 15, 2026
June 1, 2026
1.6 years
June 9, 2026
June 9, 2026
Conditions
Outcome Measures
Primary Outcomes (1)
The relationship between progesterone levels and different follicular sizes on day 7 post ovulation induction.
Progesterone levels will be measured 7 days after ovulation induction to relate them to different follicular sizes.
From the start of the menstrual cycle until 7 days after ovulation induction.
Secondary Outcomes (2)
Estradiol evolution throughout the cycle and its relation to luteal progesterone levels.
From the start of a menstrual cycle until 7 days post-ovulation induction.
Indirect factors reflecting cardiovascular and renal adaptation in the luteal phase
From the start of the menstrual cycle until 7 days after ovulation induction.
Study Arms (8)
Follicle size 11mm
Patients with a follicle of 11mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 12 mm
Patients with a follicle of 12mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 13 mm
Patients with a follicle of 13mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 14 mm
Patients with a follicle of 14mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 15 mm
Patients with a follicle of 15mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 16 mm
Patients with a follicle of 16mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 17 mm
Patients with a follicle of 17mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Follicle size 18 mm
Patients with a follicle of 18mm when measured through transvaginal ultrasound in 2D, at time of ovulation induction.
Interventions
We will collect several blood samples: * One at day 8 of the cycle: measurements of P, E2, Na, K, CL, CO2, Osmolality, PRL, direct renin, PAC, Nt-proBNP, Relaxin-2 and VEGF. * One for cycle follow up between day 8 and ovulation: measurement of P, E2, LH * One at day 7 after ovulation induction: measurements of P, E2, Na, K, CL, CO2, Osmolality, PRL, direct renin, PAC, Nt-proBNP, Relaxin-2 and VEGF.
A transvaginal ultrasound will be performed after day 8 of the cycle to evaluate a 2D measurement of the growing follicle, as well as a measurement of the endometrial thickness to evaluate readiness for ovulation induction.
The MAP will be measured at cycle day 7 and 7 days post-ovulation induction to follow cardiovascular adaptations.
When patient is deemed ready for ovulation based on follicle size, blood results and endometrium, she will be asked to inject Ovitrelle 250 micrograms to induce ovulation in a controlled and timed manner.
Eligibility Criteria
Our study population pertains to female patients and volunteers, of the age between 18 years old and 40 years old, with a regular menstrual cycle (25-35 days) and a normal BMI (18.5-35). You are eligible if you have not used any form of hormonal contraception or copper IUD throughout the last 3 months, have not had an ovarian stimulation during this time period, and are not known with renal or cardiac disease, diabetes or hypertension.
You may qualify if:
- Age below 40 years
- Regular menstrual cycles (between 25-35 days)
- Normal BMI between 18.5 and 35
You may not qualify if:
- Underlying renal or cardiac disease
- Hypertension
- Diabetes mellitus
- Contraceptive use less than 3 months before MOCK cycle, including: IUD (hormonal and copper), hormonal patch, contraceptive pill (combination and mini), hormonal intravaginal ring, contraceptive implant, contraceptive injection.
- Ovarian stimulation during the previous three months
- History of recurrent pregnancy loss (defined as 2 or more previous pregnancy losses before 24 weeks gestation).
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
UZ Brussel
Jette, 1090, Belgium
Biospecimen
Blood samples.
MeSH Terms
Interventions
Intervention Hierarchy (Ancestors)
Central Study Contacts
Study Design
- Study Type
- observational
- Observational Model
- COHORT
- Time Perspective
- PROSPECTIVE
- Sponsor Type
- OTHER
- Responsible Party
- PRINCIPAL INVESTIGATOR
- PI Title
- Doctor
Study Record Dates
First Submitted
June 9, 2026
First Posted
June 15, 2026
Study Start (Estimated)
July 1, 2026
Primary Completion (Estimated)
February 1, 2028
Study Completion (Estimated)
September 1, 2028
Last Updated
June 15, 2026
Record last verified: 2026-06