Michel De Vos

Vrije Universiteit Brussel | VUB · Faculty of Medicine and Pharmacy

Biphasic in vitro oocyte maturation (IVM) can be offered as a patient-friendly alternative to conventional ovarian stimulation in in vitro fertilization (IVF) patients predicted to be hyper-responsive to ovarian stimulation. However, cumulative live birth rates after IVM per cycle are lower than after conventional ovarian stimulation for IVF. In di...

Purpose This survey aimed to assess the public’s knowledge and opinions on oocyte donation (OD) among a large, unselected cohort of young Belgian women, and to explore aspects that could be enhanced to promote future OD programs. Methods We conducted a quantitative, epidemiological, cross-sectional web-based survey from February 2023 to April 2023...

The study investigates whether a 3-day pretreatment course with a GnRH antagonist in the early follicular phase has an impact on the number of retrieved COCs in a GnRH antagonist stimulation protocol. This is a retrospective single center crossover study involving women who did not conceive after one GnRH antagonist stimulation cycle (“standard cyc...

Delayed puberty in girls is often related to late maturation but is occasionally the first sign of premature ovarian insufficiency (POI). POI is a condition that affects ovarian function and fertility, and its etiology is unknown in most cases. Genetic factors have recently been identified in 20–25% of women with POI, involving genes that regulate...

Purpose In this survey, we aimed to provide the description of previous oocyte donors’ profile in a Belgian tertiary fertility hospital clinic. The research question is as follows: could certain aspects be changed or improved, according to previous oocyte donors? The final purpose is to boost adherence to future oocyte donation (OD) programs, given...

Study question Do corifollitropin alfa and follitropin beta have different effects on oocyte yield and live birth rates after IVM in women with polycystic ovaries? Summary answer In patients who underwent IVM, one injection of CFA resulted in lower oocyte retrieval rates, but similar birth rates compared to three injections of FSH-B. What is know...

Study question Which reproductive health information do pupils miss in their education and what is the optimal way of building a learning platform to close that gap? Summary answer Teachers and students alike would welcome a novel fertility education platform. Ideally, the platform should organize information based on the educational objectives fo...

Study question Should a national embryo transfer (ET) policy designed in the era of cleavage stage transfers be adapted for blastocyst transfers to avoid twin pregnancies? Summary answer Double embryo transfer policy results in unacceptable high twin rates at all ages and treatment ranks which is significantly more pronounced after double blastocy...

Study question Is dydrogesterone (DYD) comparable to micronized vaginal progesterone (MVP) for luteal phase support (LPS) in hormone replacement therapy frozen embryo transfer (HRT-FET) cycles? Summary answer Ongoing pregnancy rates (OPR) at 12 weeks’ gestation were comparable between the study group using DYD and the control group using MVP. Wha...

Purpose Our objective is to predict the cumulative live birth rate (CLBR) and identify the specific subset within the population undergoing preimplantation genetic testing for monogenic disorders (PGT-M) and chromosomal structural rearrangements (PGT-SR) which is likely to exhibit a diminished expected CLBR based on various patient demographics. M...

Purpose: In the past decades, a positive attitude towards having children has been reported in young people. The current generation of adolescents is increasingly concerned about environmental cataclysm which may have an impact on their desire for children. The purpose of this study is to depict the current attitudes in Flemish adolescents towards...

Purpose What are the reproductive outcomes of women who had fertility preservation (FP) using either oocyte or embryo vitrification after fertility-sparing surgery (FSS) for a borderline ovarian tumor (BOT)? Methods A retrospective, single-center cohort study was conducted between January 2013 and December 2021. Patients with BOT who resorted to F...

Research question Can a strategy for scoring oocyte quality, based on cumulus cell (CC) gene expression, prioritize oocytes with the highest implantation potential, while limiting the number of embryos to be processed in culture and the number of supernumerary embryos to be vitrified? Design An interventional, blinded, prospective cohort study was...

Study question: Is there an increase in the total number of metaphase II (MII) oocytes between a conventional ovarian stimulation (OS) and a double uninterrupted stimulation? Summary answer: There is no increase in the total number of MII oocytes when comparing one conventional OS to a continuous stimulation with double oocyte aspiration. What...

STUDY QUESTION Do ongoing pregnancy rates (OPRs) differ in predicted hyperresponders undergoing ART after IVM of oocytes compared with conventional ovarian stimulation (OS) for IVF/ICSI? SUMMARY ANSWER One cycle of IVM is non-inferior to one cycle of OS in women with serum anti-Müllerian hormone (AMH) levels ≥10 ng/ml. WHAT IS KNOWN ALREADY Women...

STUDY QUESTION Which reproductive treatment outcomes are observed in women who underwent elective oocyte cryopreservation (EOC) and who returned to the clinic with a desire for a child? SUMMARY ANSWER Whether to warm oocytes or to first use fresh own oocytes for ART depends on age upon returning, but both strategies result in favorable reproductiv...

Premature ovarian insufficiency (POI) is a rare cause of primary amenorrhea in adolescents. For young women with uncertain etiology of POI, genetic and autoimmune testing may be recommended to assist in treatment and management decisions. This report presents a case of POI in a 16-year-old adolescent with both poly-autoimmune disease and a heterozy...

Background: While oocyte IVM is practiced sporadically it has not achieved widespread clinical practice globally. However, recently there have been some seminal advances in our understanding of basic aspects of oocyte biology and ovulation from animal studies that have led to novel approaches to IVM. A significant recent advance in IVM technology...

Study question What are the reproductive treatment outcomes in women who underwent elective oocyte cryopreservation (EOC) returning to our clinic with a desire for a child? Summary answer Whether to warm oocytes or to first use fresh oocytes for ART depends on age upon returning, but both strategies resulted in favourable reproductive outcomes. W...

Study question Among patients undergoing ovarian stimulation for ICSI, does dual trigger with hCG and GnRH agonist offer any benefit over mono trigger with hCG alone? Summary answer Dual trigger is associated with a higher number of mature oocytes without any impact on the pregnancy rate. What is known already In ART cycles, final oocyte maturati...

Study question Do children born in oocyte donation families perceive their relationships with their parents differently than children conceived trough ICSI? Summary answer No significant differences were found in the family relationships between children born in oocyte donation families (OACC) compared with controls (ICSI). What is known already...

Study question In Belgium, by law, a retention period of 10-years is standard. Is this period sufficient for women to return to the clinic and use their vitrified oocytes? Summary answer A standard cryopreservation period of 10-years seems sufficient since half of the women returned to the fertility clinic and 96% used the vitrified oocytes. What...

Study question What is the cumulative live birth rate (CLBR) from the first until the tenth consecutive blastocyst transfer, across all age-groups, if no PGT-A is applied? Summary answer Our clinical data confirm existing mathematical models: without PGT-A, a CLBR of 70.0% after three, 88.9% after seven and 95.9% after ten transfers was observed....

Study question What are the current attitudes in Flemish adolescents aged 15-19 towards having children? Summary answer While the majority of adolescents want to have children, 25% have ambiguous feelings about having children and 10% indicate a wish to remain childless. What is known already In the past decades, a very positive attitude towards...

Study question Why do some IVM cycles remain unsuccessful? Which factors contribute to failure in producing a usable embryo in IVM cycles? Summary answer Failure to obtain usable embryos after IVM was associated with oocyte dysfunction, inappropriate patient selection and unanticipated low oocyte yield. What is known already In-vitro maturation o...

Study question What is the preterm preeclampsia (pPE) incidence in selected high-risk ART patient populations when applying a first trimester screening approach to recommend prevention via aspirin? Summary answer One in five high-risk ART patients had a calculated risk >1/100 and despite aspirin prophylaxis still 22.2% of them developed pPE. What...

Study question Does late follicular phase stimulation yield similar outcomes compared with conventional early follicular phase stimulation in a GnRH antagonist protocol in oocyte donors? Summary answer Late follicular phase stimulation is not inferior in terms of number of oocytes compared to early follicular phase stimulation in a GnRH antagonist...

Study question What is the predicted cumulative live birth rate (CLBR) relative to AMH-level for women undergoing preimplantation genetic testing (PGT) for monogenic disorders and structural rearrangements? Summary answer Anti-müllerian hormone (AMH) and age allow to give an estimate of the CLBR in PGT and becomes poor when AMH is ≤ 2µg/L and age...

Study question Do ongoing pregnancy rates (OPR) differ in predicted hyperresponders undergoing ART after in-vitro maturation of oocytes (IVM) compared with conventional ovarian stimulation (COS)? Summary answer One cycle of IVM is non-inferior to one cycle of COS in women with serum AMH levels >10ng/mL. What is known already Women with high antra...

Diagnosis and management of individuals who have differences of sex development (DSD) due to numerical or structural variations of sex chromosomes (NSVSC) remains challenging. Girls who have Turner syndrome (45X) may present with varying phenotypic features, from classical/severe to minor, and some remain undiagnosed. Boys and girls who have 45,X/4...

Although a wealth of data has been published regarding fertility preservation (FP) in women with malignant diseases who receive gonadotoxic treatment, the role of FP in non-malignant conditions has been studied to a much lesser extent. These include benign haematological, autoimmune and genetic disorders, as well as a multitude of benign gynaecolog...

Oocyte in vitro maturation (IVM) has been proposed as an alternative to conventional ovarian stimulation (COS) in subfertile women with PCOS. To evaluate the effectiveness and safety of IVM versus COS in women with predicted hyperresponse to gonadotropins, this study searched the published literature for relevant studies comparing any IVM protocol...

Research question: Does additional supplementation with oral dydrogesterone improve reproductive outcomes in patients with low serum progesterone concentrations on the day of frozen embryo transfer (FET) after artificial (HRT) endometrial preparation? Design: Retrospective, single-centre cohort study including 694 unique patients performing sing...

Background Inflammatory bowel diseases (IBD) affect patients during their childbearing years. Literature evidence is scarce regarding the level of knowledge among health care professionals (HCPs) and patients out the impact of IBD on fertility. The aim of this survey was to investigate HCPs' and patients' knowledge on fertility, pregnancy, and sexu...

Background and aims: Inflammatory bowel disease (IBD) can affect patients during their childbearing years. Literature evidence is scarce regarding the level of knowledge among health care professionals (HCPs) and patients about the impact of IBD on fertility. The aim of this survey was to investigate HCPs' and patients' knowledge on fertility, pre...

Background and aim: In view of their frequent onset during childbearing years, the impact of inflammatory bowel diseases (IBD) on reproductive health is of important concern to young women and to the IBD physician. This study aims to assess the fertility and assisted reproductive technologies outcomes in non-surgically treated IBD female. Methods...

Objective: Does the dose or type of gonadotropin affect the reproductive outcomes of poor responders undergoing IVF in a modified natural cycle (MNC-IVF)? Study design: This is a retrospective cohort study including patients attending a tertiary referral University Hospital from 1st January 2017 until 1st March 2020. All predicted poor responder...

Study question Is luteal phase support (LPS) beneficial in low and normal serum progesterone (P) levels the day of frozen embryo transfer (FET) in natural cycles (NC)? Summary answer LPS in case of low serum P on the day of NC-FET results in similar pregnancy rates as compared to patients with normal P levels. What is known already The use of FET...

Study question Do in-vitro maturation (IVM) of oocytes and conventional IVF (cIVF) have different effects on quality of life (QoL) in women with polycystic ovaries (PCO)? Summary answer Women with PCO who have IVM treatment experienced a lower impact on QoL compared to their counterparts who underwent cIVF. What is known already While studies in...

Study question Does female age affect reproductive outcomes in a vitrified/warmed OD program with fresh embryo transfer? Summary answer Oocyte donation performed below the age of 40 was associated with less favorable reproductive outcomes. What is known already It is well established that oocyte and embryo aneuploidy are mainly responsible for th...

Study question In case of low serum P on the day of FET (PFET), does the addition of OD to micronized vaginal progesterone (MVP) normalise reproductive outcomes? Summary answer In case of low serum PFET, adding OD results in ongoing pregnancy rates (OPR) comparable to those of patients who had normal serum PFET. What is known already Low serum PF...

Study question Is there an increase in the total number of metaphase II (MII) oocytes between a conventional ovarian stimulation and a dual uninterrupted stimulation? Summary answer Dual stimulation with continuous follicle stimulating hormone (FSH) administration is not superior to conventional stimulation in terms of number of MII oocytes. What...

Study question Can non-invasive gene expression analysis of cumulus cells (CC) improve efficiency in ART by prioritizing oocytes for further culture and fresh single embryo transfer? Summary answer CC analysis can be used for the selective processing of oocytes. This may reduce culture work and improve the outcome in ICSI elective SETs (eSET). Wh...

Study question Does progestin primed ovarian stimulation (PPOS) with dydrogesterone starting from stimulation day 6 yield similar outcomes compared with a GnRH antagonist protocol in oocyte donors? Summary answer The number of retrieved oocytes and metaphase II oocytes was similar in both stimulation protocols. What is known already The use of pr...

Objectives To study the presence of viral RNA in follicular fluid, cumulus cells and endometrial tissue samples in SARS-CoV-2 positive women undergoing assisted reproductive technologies (ART). Design Prospective, single-center, observational study. Setting Tertiary hospital, University Hospital UZ Brussel, Belgium. Patients Sixteen patients und...

Purpose As a further step to elucidate the actual diverse spectrum of oncofertility practices for breast cancer around the globe, we present and discuss the comparisons of oncofertility practices for breast cancer in limited versus optimum resource settings based on data collected in the Repro-Can-OPEN Study Part I & II. Methods We surveyed 39 onc...

Purpose To report the case of a young woman diagnosed with Turner syndrome (TS) who achieved a live birth using her own oocytes that had been vitrified for fertility preservation. Methods A 25-year-old woman with mosaic (45,X/46,XX) TS was referred for fertility preservation (FP) counseling. Serum anti-Müllerian hormone (AMH) level was normal (6.4...

Oocyte vitrification, also known as egg freezing, is increasingly used by women as a precautionary measure against anticipated fertility decline. In countries where this procedure is allowed, elective oocyte vitrification has become an integral part of the treatment portfolio of fertility clinics. The widespread tendency towards postponement of mot...

About 20% of women undergoing in vitro fertilization struggle with poor ovarian response, indicating a poor prognosis related to low response following ovarian stimulation. Indeed, poor ovarian response, that is associated with both high cancelation rates and low live birth rates, still represents one of the most important therapeutic challenges in...

Immature oocytes are a potential source of gametes in patients with a diagnosis of cancer who have no time to undergo stimulation of the ovaries or in whom ovarian stimulation is contraindicated. Immature oocytes can be harvested transvaginally from small antral follicles at any stage during the menstrual cycle without hormonal pretreatment. They a...

Research Question : The aim of the current study was to investigate the association between the development of preeclampsia (PE) and the endometrial preparation prior to frozen embryo transfer (FET). Design : We conducted a retrospective cohort study at a tertiary university-based hospital. A total of 536 pregnant patients who performed a FET betw...

Research question Do cumulative live birth rates (CLBR) differ between polycystic ovary syndrome (PCOS) phenotypes when a freeze-all strategy is used to prevent OHSS after ovarian stimulation? Design A single-centre, retrospective cohort study of 422 women with PCOS or polycystic ovarian morphology (PCOM), in whom a freeze-all strategy was applied...

Background: Bologna criteria poor ovarian responders have a very low prognosis. Although, it has been proposed that LH supplementation could be beneficial in women with previous hypo-response to FSH. There are no studies comparing the cumulative live birth rates (LBRs) between corifollitropin alfa (CFA) and highly purified human menopausal gonadotr...

Study question When repeated cycles of OS for planned oocyte cryopreservation using a standard GnRH antagonist protocol are required, can OS protocol modifications improve oocyte yield? Summary answer Compared to repeating a standard GnRH antagonist protocol, switching to a long GnRH agonist protocol for POC results in a higher number of cryoprese...

Study question Does the use of virtual reality (VR) headsets in diagnostic office hysteroscopy (HSC) with endometrial biopsy (EB) reduce anxiety and pain scores in the patient? Summary answer Virtual reality during office HSC do not seem to improve relaxation, anxiety, or pain scores. Physicians have a good perception of patients’ pain. What is k...

Study question Do cumulative live birth rates (CLBR) differ between PCOS phenotypes when a freeze-all strategy is used to prevent OHSS after ovarian stimulation (OS)? Summary answer When conventional-dose OS resulted in high response, a CLBR of ∼ 70% was observed after “freeze-all” in women with PCOS, irrespective of their phenotype. What is know...

text Discussing fertility preservation (FP) in young cancer patients has become a key component of routine oncological health care. Although ovarian stimulation followed by oocyte cryopreservation has been recommended in cases where two to three weeks are available before the start of chemotherapy, ovarian tissue cryopreservation (OTC) is the prefe...

Study question Is cryopreserved ovarian tissue transplantation safe in patients with central nervous system (CNS) tumors? Summary answer Cancer cell contamination was not detected in any ovarian samples from patients with CNS tumors by histological analysis, immunohistochemistry, molecular biology or long-term xenotransplantation. What is known a...

Study question Does the dose or type of gonadotropin affect the reproductive outcomes of poor responders undergoing MNC-IVF? Summary answer Neither the type nor the dose of gonadotropins affects the reproductive outcomes of poor responders undergoing MNC-IVF. What is known already Poor ovarian response (POR) to ovarian stimulation remains a major...

Study question Does a 3-day pretreatment course with a GnRH antagonist in the early follicular phase increase the number of oocytes in a GnRH antagonist stimulation protocol? Summary answer The administration of 3 days of GnRH antagonist before starting ovarian stimulation in a GnRH antagonist protocol increases the number of COCs (Cumulus-Oocyte-...

Study question Does the use of virtual reality (VR) headsets in diagnostic office hysteroscopy (HSC) with endometrial biopsy (EB) reduce anxiety and pain scores in the patient? Summary answer Virtual reality during office HSC do not seem to improve relaxation, anxiety, or pain scores. Physicians have a good perception of patients’ pain. What is k...

Study question Is oocyte vitrification an option for preserving the fertility of women diagnosed with Turner syndrome (TS)? Summary answer We report the first live birth achieved using cryopreserved oocytes in a woman diagnosed with mosaic Turner syndrome. What is known already Women with TS are at extremely high risk for premature ovarian insuff...

Study question What is the impact of seven days versus fourteen days’ estrogen (E2) priming on the clinical outcome of frozen-embryo-transfer in artificially prepared endometrium (FET-HRT) cycles? Summary answer No significant difference in clinical/ongoing pregnancy rate was observed when comparing 7 versus 14 days of estrogen priming before star...

Oocyte in vitro maturation (IVM) is an assisted reproductive technology designed to obtain mature oocytes following culture of immature cumulus–oocyte complexes collected from antral follicles. Although IVM has been practiced for decades and is no longer considered experimental, the uptake of IVM in clinical practice is currently limited. The purpo...

Research question To determine whether cumulative live birth rates (CLBRs) after follitropin alfa (Ovaleap®) and follitropin beta (Puregon®) are similar when used for ovarian stimulation with ICSI (Intracytoplasmic sperm injection) in a first rank GnRH antagonist protocol. Design Retrospective single centre cohort study including 832 infertile pat...

STUDY QUESTION What is the likelihood of success of a single cycle of preimplantation genetic testing for monogenic disorders (PGT-M), measured as the cumulative live birth rate (CLBR) and based on various patient demographics? SUMMARY ANSWER For all women aged ≤40 years, the CLBR was at least 10% when the number of oocytes was ≥7 (range 10–30%) o...

PurposeTo report the first successful application of in vitro maturation (IVM) of oocytes resulting in live births in two anovulatory women who had suffered oophorectomy following ovarian torsion after stimulation with gonadotropins.Methods Data abstraction was performed from medical records of two subfertile women with excessive functional ovarian...

This new edition provides a much-needed reference book to accommodate emerging and expanding knowledge in fertility preservation, the rapidly growing field of reproductive medicine associated with advances in oncology. Written by a team of world-leading experts in the field and comprehensive in its scope, the book covers the full range of technique...

Abstract Background Non-invasive oocyte quality scoring, based on cumulus gene expression analysis, in combination with morphology scoring, can increase the clinical pregnancy (CPR) and live birth rates (LBR) in Day 3 eSET (elective single embryo transfer) ICSI patients. This was first investigated in a pilot study and is now confirmed in a large p...