From an article in the June 2012 Ob.Gyn. News:
Fertility preservation for young women facing cancer therapy has garnered endorsements from leading medical groups in oncology and reproductive medicine, and it isn’t in the experimental stages anymore, interviews with experts suggest.
"There is more literature coming out showing that egg freezing does work," said Dr. Clarisa R. Gracia, director of fertility preservation at the University of Pennsylvania Health System, Philadelphia. "We have more data that we can show patients to say, ‘This is not as experimental as it used to be. It is improving, and it is a real option to offer.’ "
For example, several randomized controlled trials have shown that using frozen eggs is equivalent to using fresh eggs (Hum. Reprod. 2010;25:66-73; Hum. Reprod. 2010;25:2239-46).
The two most common methods of fertility preservation are embryo freezing and egg freezing, according to Dr. Nicole Noyes, a New York City–based reproductive endocrinologist who specializes in infertility, in vitro fertilization (IVF), and egg freezing.
Both procedures involve the use of follicle-stimulating hormone, an injectable medication that causes maturation of multiple eggs in the woman’s ovaries as opposed to a single egg that is naturally ovulated. The stimulated eggs are then gently aspirated from the ovary and placed in a Petri dish.
From this point, either the eggs can be frozen in the unfertilized state or, alternatively, sperm is added, allowing for fertilization and, thus, the creation of embryos prior to freezing. Using either method, eggs or embryos remain cryopreserved until a pregnancy is desired, at which time they are removed from liquid nitrogen for usage. In the case of eggs, fertilization is required post thaw before transfer back to the uterus.
Single girls and women who don’t have a male partner and, thus, don’t have a source of male gamete – other than donor sperm from a bank or "friend" – most often choose egg freezing, whereas women in a committed relationship more often freeze embryos.