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Egg Freezing and Your Fertility
Egg freezing, called oocyte cryopreservation, holds hope for women facing some types of cancer and/or cancer treatment that may damage their eggs or destroy ovarian function. It can also be an option for women who postpone having children because they haven’t yet found “Mr. Right,” are focused on their careers, or don’t feel their circumstances are ideal for having children. Still in its infancy, egg freezing can enable women in their 20s and early 30s to preserve their eggs and think about getting pregnant ‘down the road’ when they’re ready. And it offers an option to women who’ve produced extra eggs with assisted reproductive technology (ART) but don’t want to destroy or donate to research their unused eggs. Frozen eggs can also be thawed and used in gestational surrogacy. To date, 600 live births worldwide have been reported as a result of egg freezing.
The Process of Freezing Your Eggs
To freeze eggs, doctors stimulate a woman’s ovaries to produce a half dozen eggs (more than the regular one egg per cycle), with hormones. They then harvest these eggs from the ovaries and freeze them for later use. Egg (oocyte) quality peaks between 16 to 28 years old, women’s reproductive prime. Eggs can still be acceptable from age 29 to 38 (the mid-reproductive years) but their quality diminishes greatly from age 39 to 44.
While egg freezing could slow the pace of women’s biological clocks, the American Society for Reproductive Medicine (ASRM) warned in October, 1997, that “oocyte cryopreservation … remains an experimental procedure that should not be offered or marketed as a means to defer reproductive aging.” In other words, don’t put off pregnancy with the prospect of freezing your eggs. ASRM recommends that women exploring this option should set up consultations at fertility centers and ask about treatment options, oocyte freezing methods, success rates and policies about disposing unused eggs.
Success Rates of Freezing Eggs
Although embryos (fertilized eggs) and sperm have been successfully frozen and thawed to create healthy babies for several decades, only recently has egg freezing been successful. Sperm freezing is easier because sperm are very small - 180 times smaller than the egg cell. Egg cells have a higher water content and thus are more likely to develop ice crystals during freezing, which damages and can rupture the egg’s membrane. In 2002, the process of freezing and thawing eggs improved considerably due to the development of better cryoprotectants - the “antifreeze” that protects eggs during the freezing process - and changes in the rate with which the eggs are frozen and thawed.