What did we learn to date from the experiences of women who opted for cryopreservation of their oocytes?
Fertility psychologist and researcher Julie Nekkebroeck talks more about the experiences of women who opted for oocyte vitrification.
In vitro maturation of oocytes:
IVM is a relatively unknown assisted reproductive technology that is only available in specialised fertility centres.
A woman’s immature oocytes are collected from small follicles in the ovaries by ovarian puncture. The collected immature oocytes are matured outside the body in the lab before fertilisation. Because the punctured oocytes are immature, this treatment requires no or only a small dose of hormonal stimulation of the ovaries.
IVM was initially developed to make IVF safer and simpler for women with polycystic ovary syndrome (PCOS). Because these women have a high oocyte count, they are also at risk of developing ovarian hysterstimulation syndrome (OHSS).
Recently, IVM has also been used in women with cancer who had an IVM procedure prior to their cancer treatment as a fertility preservation measure.
IVM is simpler and cheaper than conventional IVF because it requires less hormones and follow-up treatment is less intensive for the patient.
The oocytes mature for about 30 hours in defined culture media in the lab. The mature oocytes obtained after IVM are then fertilised in the lab with sperm from the partner or from a donor using the ICSI technique. The embryos are then frozen for subsequent transfer into the uterus.
For whom?
IVM treatment can be a valid option for women with a high oocyte count. This is especially the case in women of childbearing age who have been diagnosed with PCOS or polycystic ovary syndrome.
Women with PCOS, or a high oocyte count, run an increased risk of overstimulation (OHSS) and other side effects of hormone treatment when undergoing conventional IVF treatment.
At the same time, women with PCOS also have large numbers of follicles in their ovaries. However, this high oocyte count is exactly what is needed for IVM. The treatment’s success rate largely depends on the antral follicle count. The more follicles in the ovaries, the more (immature) oocytes we can collect and mature in the lab. The more oocytes mature, the more likely that multiple embryos will develop after fertilisation.
IVM is also an option for women who have been diagnosed with cancer when there is no time for full treatment with typical stimulation or when a hormone-sensitive tumour means hormonal stimulation is not an option.
Finally, IVM can be used in a relatively rare group of women whose follicles do not respond to hormonal stimulation (FSH resistance) even though they have a normal follicle count.
IVM treatment in a nutshell
The pathway for IVM treatment is the same as any other fertility treatment.
- When you make the decision to start IVM treatment with your doctor, you will be given an appointment with an IVM counsellor.
- The IVM cycle is based on your natural cycle. If you do not have a regular cycle, your hormone levels will be determined with a blood test and a hormonal pill may be prescribed to plan your treatment.
- Treatment starts with bloodwork and a vaginal ultrasound to visualise the number of follicles in your ovaries.
- Depending on your condition, you may be asked to give yourself an injection for up to three days for mild hormonal stimulation of the ovaries.
- The next step is oocyte retrieval: we puncture the follicles through the vagina and collect immature oocytes.
The procedure is always performed under local anaesthesia. This can also be done under full anaesthesia for medical reasons.
IVM in the lab
- The oocytes we collect during the follicle puncture are left to mature in the laboratory for 30 hours in a specially developed liquid (media). In some cases, this is followed by a second 24-hour phase of in vitro maturation.
- On average, 50% of the punctured oocytes are successfully matured. Obviously, every body is different and results may vary depending on the person and cycle.
- The mature oocytes can be frozen and stored, or we can fertilise them with the sperm of your partner or a donor.
- Fertilisation is done by ICSI (injection of one sperm cell into each oocyte).
- We monitor embryo development until day 3, 5, 6 or 7 after fertilisation and freeze all embryos with a normal developmental pattern and appearance.
- The IVM counsellor will call you afterwards to let you know how many embryos were deemed good for freezing.
Am I eligible for IVM?
During a consultation, the fertility doctor will assess whether you are eligible for IVM. The main issue is whether the oocyte count in your ovaries is sufficient.
The treating doctor will evaluate this based on the results of a blood test and a vaginal ultrasound. Research has shown that the success rate of IVM in women with AMH levels is similar to that of IVF.
Want to learn more about PCOS?
Find out more about the diagnosis and counselling offered at
Five common questions about IVM answered:
Is IVM safe?
Follow-up of children born after ART treatment showed no differences in terms of risk of congenital anomalies between children born after IVM and those born after IVF/ICSI. In terms of birth weight, we also did not observe any difference between the two groups of children, nor did we observe any difference compared with children born from spontaneous pregnancy. The risk of minor and major abnormalities after IVM is less than five percent in all published studies. Research into the possible effect of in vitro culture on the epigenetic context of oocytes has also led to reassuring findings. Nonetheless, it is worth noting that several thousand children are estimated to have been born worldwide after IVM. This is in stark contrast with the more than four million IVF children who were born in recent decades. Further follow-up studies are therefore necessary and are being conducted.
Prof. Dr. Michel De Vos
What is the success rate of IVM?
Recent research at our centre has shown that for a subset of PCOS patients, namely those with a high oocyte count, the success rate of IVM treatment was at least 40% on average. For women with other conditions and/or with a lower oocyte count, the success rate of IVM unfortunately does not quite approach that of conventional ovarian hormone stimulation. However, besides success rates, we also need to take the mental and physical burden of the fertility treatment into account. In some cases, this parameter can also be a determining criterion when suggesting IVM. You should always check the success rate for your individual situation with your treating fertility doctor first.
Good to know
PCOS or PolyCystic Ovary Syndrome is a hormonal disorder that occurs in about 10% of women and is often characterised by reduced fertility due to an irregular cycle and ovulation disorders. Women with PCOS usually have a high oocyte count and can therefore use In Vitro Maturation (IVM) of oocytes, an assisted reproductive technology in which immature oocytes are matured in the lab before being fertilised.
Since when has UZ Brussel been offering IVM
This assisted reproductive technology has been applied (in a study setting) at our centre since 2009. The first IVM baby was born in 2010. In 2019, a major study based on the results of more than 1,000 women who successfully underwent IVM treatment was published. Currently, IVM is considered a routine fertility treatment rather than an ‘experimental’ technology.
What are the costs related to IVM treatment?
IVM treatment is (partially) reimbursed according to the same criteria as conventional IVF or ICSI treatment. An IVM cycle counts as one of six reimbursed IVF cycles. For women who are not entitled to reimbursement, the cost is similar to that of IVF or ICSI. In Belgium, patients receive (partial) reimbursement for six cycles of their ART treatment, if: > you are affiliated with a Belgian mutual health insurance fund > you are under 43 years of age The maximum of six cycles applies to all types of ART: in other words, you are entitled to reimbursement for six cycles of ART during your own cycle ('nature’s cycle'), six cycles of artificial insemination (IUI), and six cycles of IVF/ICSI. Frozen embryo transfer offers additional opportunities within the same treatment cycle. As a patient with Belgian mutual health insurance who is entitled to reimbursement by RIZIV/INAMI, you still pay for part of your ART yourself; the copayments. Without entitlement to this reimbursement, patients pay the full price for their treatment: follow-up, consultations, admission, laboratory fees and medication. The exact amount depends on your individual treatment.
What does oocyte retrieval or follicle puncture of immature follicles mean in IVM treatment?
Oocyte retrieval is an outpatient procedure that is performed in the operating theatre of Brussels IVF. The procedure for puncturing or retrieving the immature oocytes usually takes place under local anaesthesia, just like conventional oocyte retrieval. We know that any pain that women experience can often be attributed to the duration of the procedure. As IVM is often used in women with a high oocyte count, there may lots of follicles to puncture. You will therefore be given additional painkillers intravenously as a preventive measure during treatment.