Oocyte cryopreservation, or egg freezing as it is more commonly known, is an amazing opportunity for women to stop the “biological clock”.
The peak number of eggs present in a woman’s ovaries occurred when that woman was a fetus inside her mother’s uterus. At 20 weeks gestation, women have about 6,000,000 eggs present in their ovaries. 20 weeks later, when that baby girl is born, her number of eggs has decreased by 4 million, to 2 million eggs. From the day of birth, until the day of a girl’s first period, another 75% of those 2 million eggs disappear. This leaves most women with about 500,000 eggs for their reproductive lifetimes. The reproductive lifetime lasts for roughly 500 months and each month a woman normally releases 1 egg. Therefore, if there are 500,000 eggs available for 500 months, one would think there should be 1,000 eggs available per month, of which the body chooses one. Unfortunately, women’s bodies use many more than 1,000 eggs per month during the early reproductive years, and have many fewer than 1,000 per month during the later reproductive years.
This accelerating decline in egg supply causes the natural decline in fertility seen as a woman ages. This decline in fertility becomes statistically evident between 26 and 32 years of age. At 35 the decline significantly accelerates and by 40, a woman’s fertility is roughly 10% of what it was in her early 20’s.
Over time, the egg supply diminishes and women experience a decline in infertility.
Fortunately, egg freezing represents an alternative to the natural decline in fertility. With egg freezing, a woman uses medication to stimulate her ovaries to produce multiple eggs at the same time. This medicine includes injectable hormones which are taken on a daily basis for 8-10 days. When the eggs are ready, they are removed from the ovaries through a short aspiration procedure which is performed under light-anesthesia. Once removed, the eggs are prepared in a special liquid media then flash frozen through a method called vitrification. The frozen eggs are then stored in the laboratory until the patient is ready to use them. Sometimes this time period is as little as 1 month, but it potentially can be as long as many years to decades.
While egg freezing is not a new technology, the first baby born form egg freezing occurred in 1986, the advent of vitrification in the early 2000’s has improved the efficiency of the process tremendously. Furthermore, although the number of babies born from egg freezing is still relatively small, approximately 1,000 as of 2012, the studies of these babies have found no difference in safety as compared to babies born through standard IVF.
If you have any questions about egg freezing, please contact us, one of our specialist would be happy to speak with you.