By Dr David Wilkinson, Medical Director of City Fertility Centre Melbourne.
For many reasons, egg freezing can potentially be helpful for a variety of women. These include women who may wish to try to have children at a later date, those with a genetic disorder that could limit their fertility, and cancer patients who may need to undergo chemotherapy.
The process of freezing female eggs has advanced rapidly over the past 10 years, and studies are reporting equally successful fertilisation and embryo development rates for frozen eggs as compared with fresh ones.
However, it is essential that egg freezing happens only after appropriate counselling, and at City Fertility Centre we always work hard to educate patients on the realities.
While we have many success stories, there is no guarantee that a particular woman will have a baby down the track, frozen eggs or not. However, the younger the woman is when she freezes her eggs, the better quality they will be and hence the greater chance of a successful pregnancy at a later date.
Egg freezing involves a woman’s mature eggs being developed and removed using standard IVF techniques. This process typically involves three stages of treatment: pituitary suppression, ovarian stimulation and egg retrieval.
Freezing the Eggs
City Fertility Centre uses the “vitrification” method for freezing eggs. The process involves the egg(s) being cooled so rapidly that the water molecules do not have time to form damaging ice crystals and instantly solidify into a glass-like structure. The concept is based upon the idea that if the cell is dehydrated to a certain degree and then cooled fast enough, everything will ”freeze” in place and damage will not have time to occur.
Compared with the traditional slow-freezing methods, vitrification of eggs at City Fertility Centre is delivering enhanced survival of preserved eggs and fertilisation rates nearing those of freshly retrieved eggs. A study published in Human Reproduction in 2010* also supports this position.
Storing the Eggs
City Fertility Centre follows guidelines recommended by the National Health and Medical Research Council regarding egg storage. The maximum storage time for which eggs can be kept is 10 years.
Utilising the Frozen Eggs
When the right time comes to use the frozen eggs, they are thawed and fertilised and embryos are created. The embryo is transferred back to the woman and hopefully a successful pregnancy results. Any extra embryos created can again be frozen for additional attempts if unsuccessful, or for siblings if successful.
Making the decision to freeze eggs can be a difficult one for some. The counselling staff at City Fertility Centre are available at any time to help patients make a decision regarding their treatment.
*Rienzi. L, et al., 2010: “Embryo development of fresh ‘versus’ vitrified metaphase II oocytes after ICSI: a prospective randomised sibling-oocyte study”. Human Reproduction Vol. 25, No.1 pp. 66-73.
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