Q: I'm almost 35 years old and I don’t have a prospective father in sight. Can I freeze my eggs and use them later?
A: I know your biological clock is ticking and you have heard the stories and seen the ads from fertility clinics about freezing your eggs (also called oocyte cryopreservation). You have to realize, though, that this is still an experimental procedure with no guarantees.
Worldwide, there have been a little over 150 live births from frozen eggs. The greatest number of these births was reported in Italy. The good news is that there was only one report of a congenital abnormality. This means that after an egg (oocyte) successfully undergoes freezing, defrosting, fertilization, implantation, and embryo development, it can still result in a normal child. However, this statistic of “normalcy” is based only on three years or less of follow-up studies.
The biggest problem encountered by the reproductive specialists in their attempts to freeze eggs is that they are prone to damage by ice crystals. As an egg is frozen, the liquid water in the cell solidifies into ice and starts to expand. This expansion puts pressure on the cell and may damage its components. The integrity of the cell is also difficult to preserve when the egg is thawed. The water generated in the cell by melting the ice causes a decrease in the inside pressure (osmotic pressure). As a result, a portion of the egg can absorb water, swell, and even rupture.
There have been some advances in protecting the egg during the freezing and thawing process. The egg can be placed in solutions containing cryoprotectants. A rapid freeze method called vitrification has been successful in preserving the egg, as has a method that uses slow freezing together with the cryoprotectants to slow the metabolic rate of the egg, so that it less likely to be damaged. (This is probably way more egg physics than you want to know!)
Depending on what method is used to freeze and defrost the egg and the lab in which it’s done, recent studies show that around 20 oocytes are needed to achieve pregnancy in women under the age of 35. There have been very few studies of women over 35, but in all probability even more oocytes will be needed. Harvesting this many poses problems. You can retrieve these eggs during a woman’s natural cycle. (The retrieval is accomplished by inserting a needle through the vagina under ultrasound guidance.) However, this only yields one or two oocytes. To get more, a woman must undergo ovarian stimulation with fertility drugs for several cycles.
The more established use of oocyte cryopreservation is for younger women who have been diagnosed with cancer and who must undergo chemotherapy or radiation that will destroy the eggs in their ovaries. In 2001, approximately eight percent of the 625,000 women diagnosed with cancer were under the age of 40. Many of these women will survive their illness and may want children after their therapy is completed. Oocyte cryopreservation could allow them to do this. The question remains, however, whether it is safe for these women to undergo the necessary hormonal fertility therapy before their cancer treatment. This will depend on the type of cancer. Oncologists might prefer not to cause an increase in estrogen production in women diagnosed with breast cancer. An alternative to oocyte cryopreservation, especially for women who require cancer therapy, has been achieved through transplantation of their ovarian tissue. A portion of a woman’s ovary has been removed, stored, and replaced, and a successful pregnancy with the replanted ovarian tissue was achieved. Again, this is highly experimental.
Currently, it is much easier for women who want future fertility options to undergo in vitro fertilization, which can yield embryos that are preserved. The freezing and subsequent implantation of an embryo has a much higher success rate than that seen with freezing eggs. (If you don’t have someone you can create an embryo with and you don’t want to use a sperm donor, obviously this method is not for you.)
Finally, there’s also the possibility of using an egg donated by a younger woman when you are older and decide you are ready to get pregnant (and know from whom or where you will get the sperm). In vitro fertilization success rates depend on the age of the egg, not the age of the recipient. If a younger egg is fertilized with the donor of your choice, your chance of a successful pregnancy is as high as that of the woman whose egg was used.
Before you bemoan your lost fertility, know that it’s still possible for you to attempt conception on your own for the next five to seven years. Your potential success rate in achieving a viable pregnancy does diminish with age, but it doesn’t fall to zero. By the age of 40, though, you should not just wait for it to happen “naturally” … get to a fertility care specialist.
Dr. Reichman’s Bottom Line: Don’t count on your eggs after they’re frozen. At this point, oocyte cryopreservation is experimental and there are no guarantees.
Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.