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Egg Freezing (Oocyte Vitrification)

Vitrification (or freezing) is technology used for freezing eggs or embryos and is available at Fertility Solutions. Human sperm and embryos have been successfully frozen for decades and both are considered routine and consistent technologies.  On the other hand, human egg freezing is still a relatively new technique with the first successful report of a frozen human egg generating a pregnancy being in 1983.

While more and more fertility clinics are offering egg freezing, as a newer technology it is too early to give the precise success rates of achieving a pregnancy and live birth from eggs that have been frozen, thawed and then fertilised. It has been suggested that the freezing and thawing methods may disrupt some of the components within the egg and therefore increase the potential for chromosome abnormalities in some of the resulting embryos produced from this procedure.

The goal of egg freezing is to attempt to preserve some fertility in women at risk of declining fertility. It is not a guarantee that a pregnancy or baby will result from the use of this technology.

Storage Dewar

Storage Dewar – This is a device in which liquid nitrogen is contained and biological material, such as eggs/embryos are stored indefinitely.

 
What does this mean for women?

There are many instances when egg freezing can be used to help preserve fertility. This may be because women have focused on a career, financial stability – or have only just found “Mr Right”. Another reason that women would consider egg freezing is for medical purposes when she has a serious illness and treatment, which may leave her infertile (e.g. cancer treatment).

It is important to know that a woman’s fertility is at its peak at around 27 and slowly declines from this point until menopause. There is a significant decline in a woman’s fertility from around 35 which becomes even more significant from 38 onwards – by the age of 40 approximately 90% of eggs produced by a woman are abnormal.

Unlike a woman who continues to age, the eggs that have been frozen when she was 32 stay the same age that they were when they were frozen. So, what does all this mean? It means that a woman freezing her eggs at 32 who then wants a baby at 40, has a much higher chance of having a healthy pregnancy and baby using her 32-year-old frozen eggs than she would if she were to try with her own 40-year-old eggs.

How many eggs will I need to freeze?

The chances of success are largely determined by female age at the time of freezing and the number of eggs she is able to freeze.  The graph below, can be used as a tool to predict the chance of having a live birth (baby) with a particular number of frozen eggs at each age.  Furthermore, the table below outlines the estimated number of eggs to freeze, by female age, for women who wish to have a high chance (~95%) of having one or more babies.  Taking all these factors into consideration, this means that more than 1 IVF cycle may be required to get adequate numbers of eggs for freezing and desired outcome.

 

 

 

Graph 1. Live birth predictions by age and number of mature oocytes retrieved.

Goldman et al 2017, Human Reproduction. 

 

How are eggs frozen and stored?

All mature eggs collected undergo a freezing process and are stored in liquid nitrogen at Fertility Solutions.

How long can eggs be stored?

Eggs can technically be stored indefinitely once frozen however, the storage of eggs is regulated through the National Health and Medical Council’s (NHMRC) Ethical Guidelines along with clinic policy. These guidelines stipulate that it is not desirable to leave eggs stored indefinitely and that a clinic MUST have clear policies that limit and outline the storage duration.

Fertility Solutions policy is that eggs can be stored for a maximum of 15 years (which includes 10 years, plus a 5-year extension period). Please speak directly with our clinic if you have questions around the length of time eggs can be frozen and stored for your situation.

Your eggs will remain in storage, unless you request to use them for fertility treatment, indicate you no longer wish to store them (via signed consent) or in the event of your death (upon receipt of a death certificate).

Who may benefit?

Women who are faced with the following may find egg freezing suitable for them:

  • Advancing female age – that is women who are in their early to mid-30’s who have to delay having children because of the lack of a stable relationship
  • Women who wish to delay having children until the late 30’s for reasons other than not having a suitable partner
  • Treatment of medical conditions that may leave a female unable to have children (i.e. cancer treatment).

The use of egg freezing therefore makes it possible for women to pursue careers and relationships or undergo lifesaving treatments, with the chance of future success.

How will the eggs be collected?

A woman considering freezing her eggs would need to go through an IVF cycle which consists of stimulating the ovaries with specific hormone injections designed to make the ovaries produce an increased number of eggs, rather than the one egg that is normally produced per month.

The egg collection procedure is performed as a day procedure under a general anaesthetic. You can generally expect to leave hospital around 4 hours after the egg collection.

When can the frozen eggs be used?

When the frozen eggs are required, they would undergo a thawing process within the laboratory. It is expected that between 70% and 80% of frozen eggs survive the freeze/ thaw process.

For successful fertilization to occur the thawed egg(s) need to have a single sperm injected directly into it, this procedure is known as Intra Cytoplasmic Sperm Injection (ICSI). Not every thawed egg will fertilise however it is expected that approximately 70-60% of frozen oocytes, injected with sperm, will fertilise.

Once an egg has been fertilised, an embryo develops and the best quality embryo will be transferred into the woman’s uterus, either 3 or 5 days after thawing.

 What can go wrong with the process?

The process of egg freezing is continually being revised and updated. Sometimes things can go wrong. Some of these things are outlined below:

  1. No eggs are collected at the egg collection procedure. The reported incidence of this complication happening is less than 5%.
  2. The eggs collected are not mature and therefore may not be able to be suitable to inject in the future. This complication is not common and would be seen in less than 5% or cases.
  3. None of the eggs frozen survive the thawing process. This complication is more likely to be seen when the number of eggs collected are low.
  4. None of the thawed oocytes fertilise even though the sperm was injected into them. As with the above, this situation is more likely to occur when the numbers of eggs injected are low.
  5. A pregnancy test is negative despite having embryos transferred into the uterus.
  6. A pregnancy may be confirmed but does not continue to develop i.e. miscarriage or ectopic pregnancy. This can also occur by natural conception.
  7. A baby may be born with an abnormality. 2-3% of all babies born are reported to have an abnormality and is not necessarily related to having had fertility treatment.

It must be noted that all the above scenarios can occur under normal IVF procedures.

Counselling

Women considering egg freezing as an option must be aware that it does not give a guarantee that a healthy, live baby will be the result. Fertility Solutions encourages women to talk with a counsellor or specialist about this decision – so that all possible aspects can be considered. If you would like to talk with a counsellor, please ask your nurse who can arrange this for you.

 Speak with a Scientist

Fertility Solutions offer a free consultation with one of our Scientist to discuss any questions you may have about the process of egg freezing.  If you wish to book a confidential consultation with a Scientist, please call the Clinic on 1300 FERTILITY (1300 337 845).

 References:

R.H. Goldman, C. Racowsky, L.V. Farland, S. Munné, L. Ribustello, J.H. Fox, Predicting the likelihood of live birth for elective oocyte cryopreservation: a counseling tool for physicians and patients, Human Reproduction, Volume 32, Issue 4, April 2017, Pages 853–859, https://doi.org/10.1093/humrep/dex008