Your ART treatment at UZBrussel CRG in practice

Frequently Asked Questions of patients

Sound advice

What can I do to give my treatment a greater chance of success? Read it all here.

And click Folic acid if you want to know what every woman who wants to be pregnant should know about it.

Do we have to inform people that we are having treatment?
Will IVF deplete my supply of eggs?
Is hormone treatment harmful?
Does ART treatment increase the risk of multiple pregnancies?
Does IVF reduce the risk of an ectopic pregnancy?
How can we be sure the transferred embryo(s) is (are) ours?
Is the use of frozen embryos a good idea?
What happens with our frozen genetic material?
Do ART children have more abnormalities?
Can we choose the sex of our baby?


Do we have to inform people that we are having fertility treatment?      

It is advisable to inform certain people.
Women who do not work from home should inform their employers as soon as possible. During your ART treatment, you will have several appointments at the hospital. It is easier if your employers know the real reason for your absence.
With an honest approach, people will probably be more understanding if you are distracted due to stress or the physical discomforts during the treatment. Being able to discuss your feelings with family of friends can also be a form of support and relief.
It is best not to tell everyone you know though. Otherwise you will be bombarded with questions about your progress which can become stressful especially if there is no resulting pregnancy. Both professionally and privately, you'll probably find that one or two people to confide in are enough.
You're afraid to tell others you have a fertility problem? Well don't. 10-20% of couples experience some kind of fertility problem. But if you find it difficult to talk to other people about it, you can always get support from your counsellor at the CRG.


Does ovarian stimulation affect my supply of eggs and cause early menopause?     

Absolutely not. During the stimulation, ten or more follicles are developed at the same time but this is also the case in a natural cycle. The only difference is that in a natural cycle only one or two follicles reach full maturity whereas in IVF they can all reach full maturity. In other words, ovarian stimulation makes eggs available which would otherwise be lost.
Moreover, a woman has a supply of over 400,000 eggs at the start of her fertile years, the majority of which are lost over time. Stimulation uses a huge supply of eggs, most of which are never used.          

Is hormone treatment harmful?     

It is true the administered hormones can cause side effects. However, they are not dangerous and only temporary. Only in case of OHSS – Ovarian hyperstimulation syndrome – a medical intervention may be necessary.
Claims that the hormones used in an IVF treatment are carcinogenic is not based on any medical fact.
Moreover, these hormones have been administered to women with fertility problems on a large scale long before IVF and there have never been any reports of harmful side effects.
The effect of hormone treatments is still subject to worldwide research though. Just to be on the safe side.         

Does IVF reduce the risk of an ectopic pregnancy?      

In women who conceive naturally, there is a 1% chance of an ectopic pregnancy. In women who become pregnant through IVF, the chance is not higher unless a woman has damage to her fallopian tubes.
It is not difficult to understand why IVF treatment might lead to ectopic pregnancy. Despite careful transfer of the embryos to the uterus, they don't implant immediately and can sometimes drift into the fallopian tubes and implant there. In this case the pregnancy must be terminated (see termination of ectopic pregnancy).          

How can we be sure the transferred embryo(s) is (are) ours?       

The CRG applies strict and reliable identification procedures for eggs, sperm and embryos
See the chapter on quality care at the CRG and more specifically the information on IVF Witness.
In short: this system in fact excludes mistakes, i.e. 'mix ups.           

Is freezing embryos for later use a good idea?        

The Belgian law on ART specifies that prior to commencing your treatment, you must decide what needs to be done with supernumerary embryos, i.e. embryos that originated from your treatment but didn't need to be transferred (in this ART cycle).
In the "Use of supernumerary embryos" contract you decide whether you want to have them frozen or not.
If you do, the law says you first have to use the frozen/thawed embryos at the next IVF attempt. This is referred to as FRET (Frozen Embryo Transfer).

But is this a good thing for you as a patient? The answer is simple... yes.
  • FRET is less strenuous than IVF:
    • there is no hormonal ovarian stimulation, and
    • there is no egg retrieval.
  • The chance of embryo implantation is usually the same as with a fresh attempt.
  • For Belgian patients who are entitled to a refund of their treatment by the health insurance, these are extra attempts. The refund applies to (maximum) six attempts with fresh material.
  • It is also a fact that not all embryos survive the freezing, or rather, the thawing process.
    In other words, you need to have a number of embryos to have a reasonable chance that your next attempt will be with thawed embryos.
  • To date, the misconception that frozen embryos produce more babies with abnormalities is not supported by any research.

There is also a moral aspect to consider.
In the "Use of supernumerary embryos" contract you have to decide what to do with the frozen embryos once you have no (further) need for them:
  • donation to other prospective parents (not in every situation);
  • donation to scientific research (with possibility to specify what research you don't want); or
  • destruction..
You might have moral difficulties afterwards with the option you choose. However, you can always change your decision for as long as your embryos are frozen of course. But of course you can no longer decide not to freeze them.
See also the next question: What happens to our frozen material when our personal life situation changes?

What happens to our frozen material when our personal life situation changes?      

At the start of your fertility treatment every patient has to sign a form in which you specify what needs to be done with your frozen genetic material once you have no (further) need for it.
  • A man has to decide what to do with frozen sperm or testicle tissue.
  • A woman has to decide what to do with eggs or ovarian tissue. 
  • As a couple (or single prospective mother) you need to decide what to do with supernumerary embryos.
There are three possibilities:
  • donation to other prospective parents (not in every situation),
  • donation to scientific research (with possibility to specify what research you don't want), or 
  • destruction.
Your decision applies for the following situations.
  • If the legal storage period has expired or if you want to terminate the storage.
  • If you die.
  • If you are no longer able to make decisions independently.
  • If you divorce the partner with whom you decided to freeze embryos.
    Partners cannot use these supernumerary embryos for a possible treatment with a new partner.
As long as the agreed storage period is in effect your decision can be revised, but this needs to be a unanimous decision: each revision needs to be signed by both original partners.

Do IVF children have more abnormalities?        

Children born following ART treatment at the CRG are examined by the Centre for Medical Genetics (CMG) at the ages of two months and one year. Children born following PGT treatment – who were genetically examined as an embryo before being transferred tot the womb – are also examined at the age of two.
Abnormalities are observed in about 3% of ART children. This result corresponds not only with that of other IVF centres, but also of that observed in children conceived naturally. There are no indications to suggest any increased risk.
But we continue to monitor all (new and repetitive) research. Particularly when new techniques are used we strictly monitor ART children born as a result of this.
And worldwide the research covers various generations now: some studies focus on the descendants of (adult) ART children.

Can we choose whether we have a boy or girl?        

Nowadays it is possible to determine the sex of an embryo before it is transferred to the womb. However, sexual selection is only done if there is a specific medical reason, for example the risk of hereditary conditions which affect only one sex.
Sex selection based upon personal choice is not possible for ethical reasons. Anyway, choosing the sex of embryos without genetic indication is prohibited in Belgium.
Why not?
Medical practice
The answer to the question is simple: no, the risk is very small.
Because we do all we can to avoid this from happening.
In case of IVF|ICSI, Belgian law specifies that the number of embryos that can be transferred depends on:
  • the woman's age, and
  • the number of treatments she has already had.

These legal regulations not only apply to Belgian women who are eligible for a refund of their treatment by the health insurance, but all women who have IVF treatment in Belgium.


The increased risk of multiple pregnancies is a possible and unwanted side effect of hormonal ovarian stimulation. Because several eggs mature at the same time, several can also be fertilised.
In principle, the chances of multiple pregnancies depend on two factors:
  • the used medication
  • and with the number of embryos that are transferred with IVF|ICSI.
    In women younger than 37 following an IVF treatment:

Why not?     

Multiple pregnancies run an increased risk of miscarriage, premature birth, low birth weight and other complications. With triplets, the risks are so high, that in the past selective embryo reduction was applied whereby the number of implanted embryos is reduced from three to two.
The higher incidence of twins and triplets associated with IVF also explains why the perinatal mortality rate (the number of children who die between the 28th week of pregnancy and the 7th day after birth) is clearly above average. This higher perinatal mortality rate has nothing to do with the fact that fertilisation occurred in the laboratory.

Medical practise     

To avoid these health risks, the CRG has always tried to avoid multiple pregnancies as much as possible.

In case of artificial insemination and timed intercourse we check via ultrasound whether no more than three ripe follicles (>17 mm on average) are visible. If so, you have the following choices:
  • termination of treatment;
  • open only a number of follicles so that only one, maximum two remain and then inseminate them;  
  • switch to IVF|ICSI, possible in combination with vitrification of the eggs:
    • or the ripe eggs are collected via ovarian punction and fertilised in the laboratory with sperm of your partner or a donor;
    • or the ripe eggs are collected via ovarian punction and then frozen to be thawed at a later stage for in vitro fertilisation.

We already talked about the legal regulations for IVF|ICSI about the number of embryos that can be transferred:
  • for women younger than 36 only one embryo is transferred during the first and second treatment.
    Only in exceptional cases may two be transferred during the second attempt.
    For the third and other attempts maximum two;
  • from the age of 36 two embryos may be transferred at attempt no. one and no. two, and three from attempt no. three;
  • from the age of 40 there is no limitation in the number of embryos that can be transferred. The number is determined by you and your doctor.