Egg freezing, also called oocyte cryopreservation, is a technology that allows women to store their unfertilized eggs. The process involves extracting, dehydrating and freezing eggs (usually in liquid nitrogen) until they are ready to be implanted. Since 2012, the American Society for Reproductive Medicine (ASRM) no longer considers egg freezing to be an experimental procedure, but there are still a number of important caveats to consider.
How is egg freezing performed?
The entire process of egg freezing begins with meeting doctors to talk about the procedure and ways to increase your chances of successful egg retrieval. Your doctor may recommend changes like smoking cessation and avoiding alcohol during the treatment to improve your outcome.
There will be several weeks of multiple hormone therapies. You will need to inject yourself with daily doses of hormones that stimulate ovaries into producing multiple eggs and control ovulation cycles. This step, and the next one, may be repeated as necessary until enough eggs are harvested.
Once egg production is increased, the eggs are extracted using a specially designed needle that is inserted through the vagina and guided by ultrasound. The needle will reach the fallopian tubes and capture eggs without having to break the skin. The patient is sedated during the procedure, which is performed on an outpatient visit, usually at the fertility clinic.
Following this, the eggs will be dehydrated to prevent ice crystals from forming in the egg, and then they are frozen. The freezing process—cryopreservation—is similar to that of embryo freezing.
There are two methods that can be used for cryopreservation: slow freeze or vitrification.
- Slow freeze involves the gradual freezing process of cryopreservation.
- Vitrification is a newer, quick freeze technology.
Regardless of the cryopreservation method used, the eggs are stored in test tubes and surrounded by liquid nitrogen to keep them frozen until ready for use.
What are the caveats of egg freezing?
The main stipulation is that egg freezing should be considered an option when medically necessary, not as a means of choosing to delay childbearing for lifestyle reasons.
A report issued by the ASRM's Practice Committee in 2012 cautioned, "Marketing this technology for the purpose of deferring childbearing may give women false hope and encourage women to delay childbearing. Patients who wish to pursue this technology should be carefully counseled."
The chair of the committee, Dr. Samantha Pfeifer said, "While a careful review of the literature indicates egg freezing is a valid technique for young women for whom it is medically indicated, we cannot at this time endorse its widespread elective use to delay childbearing."
In addition, Pfeifer emphasized that egg freezing is for younger women, and may not be right for older women seeking to defer reproduction.
It's important to keep in mind that, according to the ASRM, IVF with frozen eggs results in lower live birth rates than fresh IVF cycles. In addition, embryo freezing is considered to be a more viable option, though it is a more invasive procedure.
Who is a good candidate for egg freezing?
Egg freezing is a fertility preservation option for young women at risk of losing their fertility due to other medical treatment (especially for cancer). Though some women use egg freezing to delay pregnancy, success rates decline with age. Egg freezing may be an option for:
- Women who are able to undertake hormone therapy to boost egg production
- Women undergoing cancer or other medical treatments whose eggs may be damaged with treatment
- Women whose religious or personal convictions prevent them from considering freezing embryos
- Younger women, primarily
Egg freezing isn’t feasible for prepubescent girls, because their eggs are not yet capable of being fertilized.
What are the risks of egg freezing?
The intensive hormone therapy required to allow a woman to produce a large number of eggs may carry some risks, depending upon the patient’s health history. Patients considering egg freezing should bear in mind that, as with any procedure, there are no guarantees of success. Statistically, unfertilized eggs have a lower chance of surviving the thawing process than fertilized embryos. Although the egg structure may survive the process, the eggs may not be viable for use in fertilization.
Age is a major factor. The older a woman is when she freezes her eggs, the lower her chances of successfully making use of those frozen eggs to get pregnant.
How long are frozen eggs viable?
As of now, eggs have been successfully used after being frozen for 10 years, but scientists are working to extend their viability.