Letrozole added to fertility treatment in women with endometriosis undergoing IVF or ICSI
Tests letrozole during ovarian stimulation in women with endometriosis having IVF or ICSI.
Key facts
- Who runs it
- UZ Brussel
- Where
- Anderlecht, Antwerp, Brugge, Edegem, Genk, Gent, Jette, Leuven, Liège, and Sint-Lambrechts-Woluwe, BelgiumSee the 11 sites
- Trial code
- Registry title
- ENDO-REAL: Endometriosis and Reproductive Enhancement with Letrozole
- Status
- Recruiting
- Phase
- Phase 4
- People taking part
- 854 people, planned
- Started
- 29 Sept 2026
- Expected to end
- 1 Jun 2031
- Type of study
- Interventional
- Record updated
- 25 August 2026
Who can take part
AI summary
From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.
The trial is looking for women with endometriosis who need IVF/ICSI treatment because of infertility. It tests adding letrozole during ovarian stimulation.
- Age
- 18 years or older and under 40 years
- Sex
- Women
- Disease stage
- Endometriosis of any type or stage, confirmed by ultrasound, MRI or surgery. Adenomyosis may also be present. The woman needs IVF/ICSI, with a fresh embryo transfer planned after egg retrieval.
- Earlier treatment
- No more than three unsuccessful IVF/ICSI cycles in a row since the last ongoing pregnancy.
- Biomarker or test result
- BMI below 35 kg/m. Women with AMH below 0.5 ng/mL in the past year cannot join.
Main reasons for not taking part
- AMH below 0.5 ng/mL in the year before randomization
- Abnormal uterine cavity or untreated problem inside the uterus
- Untreated blocked tube with fluid (hydrosalpinx)
- Any untreated hormone problem
- Sperm obtained by surgery
The registry criteria, word for word
Show all 14 criteriaShow less
Who can take part
- Sub/infertile women with a diagnosis of endometriosis (all types/ stages) either by TVUS/ MRI or surgically and an indication for treatment with IVF/ICSI (based on existing guidelines) are eligible for the study
- Planned fresh ET following oocyte retrieval
- Patient with and without concomitant adenomyosis will be included
- The patient must have undergone not more than three consecutive unsuccessful IVF/ICSI cycles since the last ongoing pregnancy (whether fresh and/or several frozen ET resulted from these attempts). Each patient may only participate once
- Age ≥ 18 years and < 40 years
- Body mass Index (BMI) < 35kg/m
- Participant should be capable of giving informed consent
Who cannot take part
- Severe OHSS in previous treatment cycle or patients planned in forehand for a freeze-all strategy
- Anti-müllerian hormone (AMH) < 0.5 ng/mL (dosage in the 1 year preceding randomization)
- Abnormal uterine cavity (known mullerian duct anomalies, intra-uterine adhesions or other untreated intra-uterine pathology)
- Untreated tubal factor (hydrosalpinx)
- Any untreated endocrine abnormality
- Surgically obtained sperm
- Ovarian stimulation for pre-implantation genetic testing (PGT-A/M)
Check if you might fit
Answer for yourself. This is not a decision: only the study team can say whether you can take part.
- Are you between 18 and 64 years old?
Where in Belgium
- Hopital ErasmeAnderlecht, BelgiumTaking people
- Ziekenhuis Aan De StroomAntwerp, BelgiumTaking people
- AZ ST-JAN Brugge A.V.Brugge, BelgiumTaking people
- Universitair Ziekenhuis AntwerpenEdegem, BelgiumTaking people
- Ziekenhuis Oost-LimburgGenk, BelgiumTaking people
- Universitair Ziekenhuis GentGent, BelgiumTaking people
- UZ BrusselJette, BelgiumTaking people
- UZ LeuvenLeuven, BelgiumTaking people
- Centre Hospitalier Regional de la CitadelleLiège, BelgiumTaking people
- CHC MontLégiaLiège, BelgiumTaking people
- Cliniques Universitaires Saint-LucSint-Lambrechts-Woluwe, BelgiumTaking people
About the trial
What the trial wants to find out
The primary objective of this study is to determine whether letrozole co-administration during ovarian stimulation for IVF/ICSI can improve the occurrence of a live birth following embryo transfer(s) in patients diagnosed with endometriosis +/- adenomyosis. Primary outcome will focus on cumulative live birth per stimulation cycle, including fresh and frozen embryo transfers resulting from the same oocyte aspiration and transferred within 1 year (52 weeks) of randomization. Live birth following fresh embryo transfer and number of ETs needed for successful pregnancy will also be evaluated as an important outcome.
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Contact the study team: see the registry record
Print a page for my doctorData and sources
- Registry record
- Listed on the EU's official list of trials (CTIS).
- Official title
- Reproductive outcomes with letrozole co-treatment during ovarian stimulation in women with endometriosis undergoing IVF/ICSI: a randomised, multicentre, parallel group pragmatic trial
- Plain-language title
- Letrozole added to fertility treatment in women with endometriosis undergoing IVF or ICSIGenerated from the registry record. The registry title is the official one.
- AI summary
- From the trial's eligibility criteria. Read by machine on 9 November 2026.
- Fit questions
- Built from 2025-524995-53-00, who can take part
- Record updated
- 25 August 2026