Research by the world’s largest assisted reproduction group, IVI, has revealed some vital statistics concerning fertility preservation. The results will be of compelling interest for those considering the possibility of delaying motherhood through the freezing of oocytes. They found that success rates were significantly higher – showing a 40% increase – when the first stage of the process is carried out at under 35 years of age. It follows that the best chance of getting pregnant as a result of this treatment is when it is conducted at the optimal time. On the other hand, the majority of women who opt for this process for social as opposed to medical reasons are over 35 years old.

In this IVI blog article we look at the reasons for this apparent mismatch and explain how IVI came to its conclusions. We also take an in-depth look at oocyte vitrification, one of the fastest-growing fertility treatments.

Vitrification of oocyte success rates: key findings from IVI

With more than 65 clinics in 11 countries, IVI is the leading centre for reproductive medicine. It is also at the forefront of developing pioneering techniques and undertaking research into trends in how these techniques are accessed. Its most recent research has been published in the prestigious journal Human Reproduction. The study was led by Dr. Ana Cobo, director of the IVI Cryobiology Unit. It examined fertility preservation undertaken for both medical and elective social reasons and the factors that influence the outcomes. It addresses women’s primary concerns about fertility preservation and provides interesting statistics on success rates and resulting pregnancy rates that patients who have their eggs vitrified can achieve.

Dr. Cobo explains, “What is very striking is that while women under the age of 35 years who preserved their fertility for social reasons achieved a success rate of 94% by obtaining 24 oocytes to vitrify, those who were over 35, with a similar number of oocytes, barely reached a 50% probability of full-term pregnancy. Hence the importance of preserving fertility before the age of 35, something we always emphasize at IVI in our awareness of the effect of age on oocyte quality”.

We see that there is no difference between the under and over-35s in the number of oocytes which can be obtained for vitrification as part of the fertility preservation technique. The results, however, highlight that the main marker of oocyte quality is the patient’s age. The results present a clear advisory guide on the best chances of getting pregnant as a result of the oocyte vitrification. These results help to outline the statistical reality which can be highly significant in advancing the field of preventing infertility.

Fertility treatments: what is fertility preservation?

Fertility preservation is simply an approach by which women who choose, for various reasons, to delay motherhood to a future time. It is invaluable for two main groups of women. There are those who need to preserve their oocytes because they are due to undergo cancer treatment like chemotherapy or radiotherapy which could damage their future fertility. The other group consists of women who for professional, social or economic reasons need to delay fertility to a future time.

Fertility preservation for oncology patients

This type of fertility treatment is indicated for patients who are at risk of losing their ovarian function. These could be women who have been diagnosed with cancer or autoimmune diseases which require chemotherapy or bone marrow transplants, for example, or women at risk of needing repeated ovarian surgery, for example to treat endometriosis.

Of course the timing of such treatment is less a matter of choice for this group of patients, and the IVI research did not observe the trend for increased success for those under the age of 35 when it was carried out. Researchers think that this is mainly due to the smaller sample size, and the smaller number of patients who returned to use their vitrified eggs in the study time period.

Fertility preservation for social and personal reasons

The research found that the fastest-growing sector wishing to access fertility preservation is the elective group. This is the group of women who decide to postpone motherhood as a matter of personal choice, or because their financial or work circumstances currently prevent them from having a child. In addition, the study shows a clear development of the ‘social reasons’ group, which in just over 10 years has increased by 18%, from 2% to 22% of the total number of treatments performed at IVI during the decade 2007–2017.

However, the fact remains that within these increased numbers, and in light of the growing importance of fertility preservation among the range of fertility treatments, there is still relatively low awareness of one crucially significant factor. This is the importance of age as an indicator of the egg quality, that directly impacts over the best chances of getting pregnant following the treatment. The largest group of patients who plan to preserve their fertility for social reasons continues to be those above the age of 35. In fact, the over-35s account for over 70% of the women who have preserved their fertility for social reasons at IVI, and 15% were over the age of 40 when they did so.

How does fertility preservation work?

You could think of the most commonly used technique as being the same as a normal IVF process, but with a delay of indeterminate length in the middle, during which time the oocytes are frozen. This is not the same as freezing embryos, since the vitrification takes place before fertilisation. Our video about the vitrification of oocytes on the IVI YouTube channel explains what the technique is, and what happens when it is carried out.

In both groups of patients the most commonly used procedure is oocyte vitrification. Here’s how it works:

Step 1: Ovarian stimulation

This takes place in order to be able to collect a number of mature eggs (oocytes).

Step 2: Vitrification of oocytes

This allows the mature eggs obtained following ovarian stimulation to be cryopreserved so that they can be used at a later date, when the patient decides she is ready. Vitrification is the most advanced freezing method to cryopreservation, and enables to cool the living oocytes in the absence of ice crystals, so it eliminates the risk of mechanical injury.

Step 3: The eggs remain in cryopreservation

Due to the fact that ice crystals do not form, oocyte survival rates are high, allowing motherhood to be postponed with reasonable guarantees of success. In most cases the oocytes have the same prognosis as at the point when they were vitrified and the intervening time lapse makes no difference.

Step 4: Fertilisation

When the appropriate time comes, the eggs are warmed and fertilised in vitro in the laboratory in the same way as in the normal IVF routine. Sperm from the woman’s partner or donor sperm may be used. Fertilisation is optimised with the use either intracytoplasmic sperm injection (in which a single selected sperm is inserted directly into the oocyte) or conventional In Vitro fertilisation (where each egg is cultured in a drop of processed sperm, mimicking the natural process).

Step 5: Transfer to the uterus

As with IVF, the resulting embryos are cultivated for a period in the laboratory before being placed into the patient´s uterus with the aid of a specially designed cannula.

New developments in vitrification

Of the different vitrification techniques that are available, the Cryotop method offers the best results. IVI has pioneered the incorporation of this technique and is the European leader in its clinical use. With the Cryotop protocol, survival figures of up to 97% have been achieved for young patients (those up to 35 years old), with resulting pregnancy rates of 65%. These results provide further confirmation of Dr. Cobo’s findings that the best success rates following fertility preservation treatment are when the first stage of the process is carried out on patients under 35.

Finding out more about fertility preservation

So the overall message is clear. If you feel inclined to think about fertility preservation for social or personal reasons, your best chances of getting pregnant following treatment is to plan ahead rather than wait until the biological clock starts to ring alarm bells! We would encourage anyone interested to browse our website for the most up-to-date information about this and other fertility treatments, along with our independently audited results. When you feel the time is right, do get in touch. You can call us on 08 000 850 035 from the UK or on +34 960 451 185 from other countries. You could also complete our online enquiry form with your details and we will call you back. Your information is treated with complete confidentiality and we do not share our database with any other companies.