You’ve probably seen reports in the news about hot young celebrities freezing their eggs as a sort of insurance policy — if they don’t meet the right partner by the time they hit their 40s, they’ll still have the option to get pregnant by simply thawing their eggs and adding donor sperm.
While that sounds great in theory, their expectations may not be realistic. In fact, the “egg freezing parties” that are popping up all over the country, encouraging women to delay childbearing and prolong their fertility, may actually give some women false hope.
Egg freezing, known by its technical term as mature oocyte vitrification, is not considered an experimental procedure any more. But American physicians still don’t have much clinical experience with it. So far, there have been only about 900 live births in the United States that resulted from frozen eggs.
Possible Candidates for Egg Freezing
Egg freezing is an alternative to embryo cryopreservation, where a fertilized egg is frozen for future implantation. In fact, most of the data on egg freezing comes from Europe, where it has been commonly used much longer, in part because embryo cryopreservation is prohibited in many countries there.
Women might choose to freeze eggs instead of embryos if they are undergoing chemotherapy or radiation treatment for cancer, if they have no partner or donated sperm to create embryos, or if they wish to donate their eggs.
In addition, women with certain genetic conditions, such as BRCA carriers, may want to freeze some of their eggs before they choose to remove their ovaries as a precaution against an increased risk for cancer. Couples who have ethical or religious concerns about freezing embryos may choose to freeze eggs instead of embryos as well.
How It Works
The initial treatment for egg freezing is the same as for women going through in vitro fertilization (IVF) — a fertility specialist will prescribe medication to stimulate egg production. The eggs will then be retrieved in a simple and virtually painless outpatient procedure, then the eggs are frozen for future use.
When the patient decides she wants to try to get pregnant, the eggs are thawed in a lab and mixed with partner or donor sperm via intracytoplasmic sperm injection (ICSI). The embryos are then grown and transferred just like in a regular IVF cycle. For more about how IVF works, click here.
One challenge is that eggs are harder to freeze than sperm because they are larger and have a higher water content. In the past, fertility experts used a slow-freezing method, where the egg’s temperature was cooled gradually. This method increased the risk of ice crystal formation, which could affect the survival of the egg when it was thawed. Now, most doctors are using a process called vitrification, in which the egg is plunged into liquid nitrogen. In this newer method, there is less risk of ice crystals and a higher survival rate for the eggs when they are thawed.
If you’re counting on getting pregnant using frozen eggs 10 or 20 years from now, you should know that your success may depend on the maternal age when your eggs were frozen. An older woman’s eggs (over age 35) have a higher risk for chromosomal abnormalities and are less likely to result in a healthy pregnancy. Also, be aware that the chances for achieving a successful pregnancy — no matter what method — decreases in general with a woman’s age.
There is not a lot of data available on U.S. success rates for egg freezing, and most of it has been compiled on women who are younger than 30 years old. Some studies have shown a survival rate after thawing of 90%, fertilization rate of up to 79%, implantation rates of 17-41%, and clinical pregnancy rates per thawed egg of 4-12%. Of the babies born in the United States as a result of egg freezing, there appears to be no difference in birth defects and weight than that of children conceived naturally, but there has been no long-term follow up yet.
There is also limited data on how long the eggs can safely be stored frozen — most of the eggs frozen in the U.S. have not yet been thawed and used to create embryos. Only time will tell if they will result in successful births.
As you can see, egg freezing is not exactly a guarantee that a woman can start a family later in life. While it may offer an extra option, we advise you not to put all your eggs in one basket — pun intended.
If you’d like to learn more about the fertility treatment options we offer, call us for a consultation at (502) 897-2144.