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Saturday, December 8, 2012

Freezing eggs -- no longer experimental.



The Practices Committees for the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology have reviewed data regarding the role of cryopreserved oocytes in fertility medicine, and they recommend inclusion of this practice where appropriate in clinical medicine. In other words, they declare that the practice is no longer experimental.  Well, they do offer one cautionary note:  freezing oocytes for the purposes of delaying childbearing, for reasons entirely unrelated to health.  But their own analysis opens the door to doing exactly that, under some circumstances.

The Committees report that similar success rates exist whether using vitrified oocytes or fresh oocytes for IVF/ICSI in regard to fertilization and pregnancy rates. They report no increase in chromosomal abnormalities or birth defects compared to conventional IVF/ICSI. 

The Committees recommend that cryopreserved oocytes can therefore be recommended as appropriate when managing gonadotoxin therapies, ovarian excision, premature ovarian failure, unavailability of sperm from intended partner, and as an alternative for those unable or unwilling to cryopreserve embryos.

The Committees decline to recommend the use of cryopreserved oocytes for – as they say – the sole purpose of circumventing reproductive aging in health women. They say that no relevant data exist for these so-called ‘social reasons’ for wanting cryopreserved oocytes. Relevant data are non-existent they say for the safety, efficacy, cost-effectiveness, and emotional risks. They worry that marketing cryopreservation of oocytes as response to reproductive aging may give false hope and encourage postponement of childbearing.  This would be a mistake they say because of the low success rates for pregnancy of women as they age, especially those who freeze their oocytes after age 38.

Strictly speaking, data may be missing for this group of women, but it is unlikely to be materially different from other uses of cryopreserve oocytes. A woman who freezes oocytes for social reasons may not leave these oocytes frozen for periods longer than is done for other reasons, and the woman might not be of advanced maternal age either. For example, a woman who plans to become a surgeon might well freeze her eggs at age 22, fully intending to use them at age 33. This time span might be no different from a woman who freezes oocytes when having her ovaries removed because of a high risk of cancer. 

The Committees are right that data for these uses is lacking, but there is no reason in advance to suspect that the data that will emerge will be materially different from other uses of cryopreserved oocytes. Some uses of oocyte freezing for 'social purposes' will parallel the ways in which these oocytes are used in other circumstances. So, those are really no longer experimental either.

(The full report is at:  http://www.asrm.org/uploadedFiles/ASRM_Content/News_and_Publications/Practice_Guidelines/Committee_Opinions/Ovarian_tissue_and_oocyte%281%29.pdf )

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