Under reduced fertility we discuss the different factors which may affect a person or couple's chances of becoming pregnant.
In IVF/ICSI treatment the following aspects have the biggest effect on your chances of success.

• Your age (woman)
  The older you are, the less easy it is to get pregnant and the higher the risk of miscarriage.
• Your treatment history
  The number of previous IVF/ICSI treatments is an indication. For instance, if you have already had four failed attempts, a possible fifth treatment will not offer the same chances of success as the first. 
• Your medical profile
  Your physical condition also has an effect of course, regardless of your age. Some aspects of your physical condition you cannot control, others you can. Make sure you read our lifestyle tips.
  
  

The main factors that can affect your chances of success have been listed below.

• Are you a woman, and:
• if your ovary contains few eggs, this can have a negative effect on your chances of success (regardless of your age);
• if you have a blocked fallopian tube filled with fluid (hydrosalpinx), your chances of success are halved;
• if you smoke every day, your chances of success are also almost halved;
• if you are overweight, i.e. a BMI in excess of 25 (kg/m²), you lower your chances of success by almost one third;
• If you are a man, the quality of your sperm also determines whether you are able to father a child.
  However in practice for IVF/ICSI, this factor only affects men with a problem in their sperm production, for whom the semen for the treatment was obtained through surgery (TESE). 

Naturally there are also differences in the chances of success between the different treatment centres (in Belgium and beyond).
For 2015 the Belgian reporting shows a variation in the chances of success between the Belgian centres of 23% to 48% per embryo transfer in the so-called reference group – i.e. women younger than 36 year undergoing their first IVF/ICSI-treatment.

Expertise and quality

These differences may concern expertise and the quality of treatment. Although it is difficult to prove, investments in quality management usually result in higher chances of success.

Selection of patients

Centres do not apply the same standards in terms of the selection of patients either. Some centres will not include or refer patients with a specific medical profile for treatment. And as we already saw, your medical profile – in addition to your age and the number of IVF/ICSI attempts - is an important indicator for your eventual chances of success.

Measurement and interpretation

Many centres express the chance of success as ‘chance of pregnancy’ or ‘chances of progressing pregnancy’. This implies that miscarriages are always included and the figures look better than they are in actual fact.
The chances of success are sometimes also expressed ‘per embryo transfer’. This too could paint a flattering picture of the chances of success, because patients who did not have a transfer – but did start a treatment cycle – are not included. In other words, patients with a worse prognosis – e.g. due to a low number of eggs after retrieval, the lack of fertilisation, a bad embryo development – do not show up in the figures.

This is why the CRG works with a cumulative reproduction of the chances of success, i.e. the chances of success per treatment cycle and across the cycles. This results in a more honest assessment of the chances of success, because on the one hand there is no selection of patients with a better medical profile and on the other hand, the effect of the number of attempts is also included in the calculations.

Practice has shown that it is difficult to predict your individual chances of success with an ART treatment. During the intake-consultation the CRG doctor will always try to make the most accurate assessment possible. This is based on our medical experience, but also on results of the past.
​
The chart shown here is based on the results of all CRG patients who started their first IVF/ICSI treatment in 2011, without any selection (read ‘exemption’) based on their medical profile. See The Lancet paper.

For a number of age categories the chart shows

• the expected cumulative chances (i.e. across various attempts),
• of a delivery (i.e. not pregnancy or progressing pregnancy),
• after every started cycle, the egg retrieval which yielded at least one egg, and/or
• after the possible transfer of fresh embryos and possible frozen-thawed embryos – and with strict application of the legal standards regarding the number of embryos that can be transferred.

• On the vertical line you can see how many women (out of a hundred) in which age category will have delivered a baby after IVF-ICSI-treatment with possible transfer of fresh and frozen-thawed embryos.
• The horizontal line shows the number of treatment cycles.

Example for age category up to 36

• Expectations are that 47 out of 100 women who start IVF-ICSI will deliver a baby after their first treatment cycle.
• If the women who did not deliver a baby after the first cycle, start a second cycle, 63 of the original 100 will have delivered a baby.
• After the third treatment cycle, 74% will have delivered a baby. And so on.

The effect of age is obvious:

• at a young age you easily become pregnant: the first treatment cycles result in a high chance of pregnancy;
• at a later age every treatment cycle results in a comparable but lower cumulative chance of pregnancy:
  • because it is more difficult to get pregnant (lower chance of implantation), and
  • more difficult to stay pregnant (higher risk of miscarriage);
• for the group of women in the 40 to 42 age category ten out of a hundred who start the first treatment cycle will deliver a baby. After the fourth treatment cycle, 38 women out of a hundred will have delivered a baby.

In short, whereas in the youngest age category almost 9 out of 10 women has had a baby after six treatment cycles, in the 40 to 42 age group this is only 45%.
Beyond the age of 42 the chances of success of women who were not selected based on a better medical profile is limited: less than ten percent will deliver a baby.

And finally, if IVF/ICSI treatment with your own genetic material is without result, often due to age, it is still possible to use donor material, i.e. donor eggs or donor embryos.