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Updates in Egg Freezing
a blog by Genna Banafato, June 23, 2013
Fertility is finite. Women are born with a determined number of eggs. The majority of women have heard these phrases at one point or another and most understand they refer to the decreasing likelihood of getting pregnant as we get older. Up until now, as women get older and more concerned about the status of their fertility, the only option available to us has been advanced reproduction techniques, such as IUI (intrauterine insemination) and IVF (in-vitro fertilization).
As the ASRM (American Society for Reproductive Medicine) removes the "experimental" label from egg freezing and recent legislature in California (requiring insurance companies to pay for egg freezing for the sole purpose of fertility preservation in cancer patients) comes up for vote, more and more of the focus seems to be on oocyte cryopreservation. I spoke with Dr. Serena Chen of IRMS at St. Barnabus in New Jersey to find out some of the facts behind this recently developing science.
Sperm has been frozen, thawed and successfully used for fertilization for years. Egg freezing has proven more challenging due to the size of the cell. The freezing method used for sperm has proven ineffective for eggs. Eggs are a much larger cell with a large volume of water inside. Early methods used to freeze eggs led to crystal formation inside the cell. These crystals caused the eggs to have low survival rates. Even if the eggs survived the thawing process, they proved impossible to fertilize. However the new technology used to freeze eggs has greatly improved the fertilization rates. According to Dr. Chen, these thawed eggs have a 0% fertilization rate without Intracytoplasmic sperm injection (ICSI) but with ICSI, fertilization rate is 50-80%. Additionally, she says that most programs will do assisted hatching on anything that has been frozen, with the exception of a blastocyst, due to the thinner zona.
This is very exciting technology. Male cancer patients have had sperm freezing as an option for decades, to preserve their fertility prior to starting treatment. Now that ASRM has changed their guidelines as of October, 2012, female cancer patients should now have that option as well. Dr. Chen cautions, however, that elective egg freezing (as in freezing eggs to "pause their biological clock") is still not considered routine.
Much like any other ART, there is no "one size fits all" approach. Treatment and recommendations should be based on the individual patient. However, as this research takes an exciting step forward, it will hopefully continue to open new doors to treatment of infertility.