Success Rates
The percentage of transferred cycles is somewhat lower in frozen cycles compared with fresh cycles (approx. 80% and 90%, respectively). Such outcomes are considered comparable.
Two recent studies showed that the rate of birth defects and chromosomal defects when using cryopreserved oocytes is consistent with that of natural conception.
Recent modifications in protocol regarding cryoprotectant composition, temperature and storage methods have had a large impact on the technology, and while it is still considered an experimental procedure, it is quickly becoming an option for women. Slow freezing traditionally has been the most commonly used method to cryopreserve oocytes, and is the method that has resulted in the most babies born from frozen oocytes worldwide. Ultra-rapid freezing or vitrification represents a potential alternative freezing method.
In the fall of 2009, The American Society for Reproductive Medicine (ASRM) issued an opinion on oocyte cryopreservation concluding that the science holds “great promise for applications in oocyte donation and fertility preservation” because recent laboratory modifications have resulted in improved oocyte survival, fertilization, and pregnancy rates from frozen-thawed oocytes in IVF. The ASRM noted that from the limited research performed to date, there does not appear to be an increase in chromosomal abnormalities, birth defects, or developmental deficits in the children born from cryopreserved oocytes. The ASRM recommended that, pending further research, oocyte cryopreservation should be introduced into clinical practice on an investigational basis and under the guidance of an Institutional Review Board (IRB). As with any new technology, safety and efficacy must be evaluated and demonstrated through continued research.
In October 2012, the ASRM lifted the experimental label from the technology, citing success rates in live births, among other findings.
Read more about this topic: Oocyte Cryopreservation
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