Egg Freezing Services
Egg freezing at a glance
- Egg freezing allows a woman to preserve and, in some cases, extend her fertility.
- Although embryo freezing (cryopreservation of fertilized eggs) is still the preferred method, the freezing of unfertilized eggs has become a standard clinical practice to preserve a woman’s ability to have biological children, and is no longer considered experimental by the American Society of Reproductive Medicine.
- The egg retrieval process is the same as that used in IVF.
- A woman’s eggs can be frozen and stored indefinitely.
What is egg freezing?
Egg freezing, or human oocyte cryopreservation, helps women effectively slow down their biological clocks by freezing and storing unfertilized eggs. When a woman decides to start a family, the eggs are thawed, fertilized and placed in her uterus.
Egg freezing has gained greater acceptance following the American Society for Reproductive Medicine’s finding in October 2012 that the procedure is no longer considered experimental and can now enter into standard clinical practice.
Embryo freezing – the freezing of a fertilized egg – is still the preferred technique for fertility preservation because freezing unfertilized eggs can be more difficult, due to the cells’ high water content. However, young or single patients who don’t want to use a sperm donor may now opt for egg freezing.
The egg freezing process
Egg freezing, which costs between $10,000 and $15,000, on average, occurred in as many as 200 medical centers across the country at the end of 2011, according to news reports.
The egg retrieval process is the same as for in vitro fertilization (IVF). A woman’s ovaries normally develop one egg per month, so for egg retrieval the woman will take hormone injections for several weeks to stimulate the ovaries to develop multiple eggs at a time.
When the eggs are mature, the woman takes a medication to trigger ovulation. The doctor removes the eggs from the ovaries using an ultrasound-guided needle inserted through the vagina. The woman is under sedation during the retrieval process. The eggs, about the size of a pencil point, are then frozen.
Laboratories’ freezing processes and use of cryoprotectants vary. Some use a slow egg freezing technique, but the preferred method is a flash freezing process called vitrification. After freezing, the eggs are stored in tubes in a liquid nitrogen tank.
In the past, it was difficult to freeze eggs due to the cell’s tendency to develop ice crystals during the freezing process, which compromise the integrity of the egg, as well as harden the egg’s outer membrane, making later fertilization difficult.
Excessive ice crystal formation can cause a cell to burst. Because the egg is a large cell, with a lot of water, it is especially prone to ice crystal formation. Excessive ice crystal formation can cause a cell to burst. By contrast, embryos are made of smaller cells and are less susceptible to ice crystal formation and therefore, easier to freeze. This is one reason why embryo freezing has long been the preferred fertility preservation method.
Recent developments in fertility treatment have improved the egg freezing process.
A new culture media system protects eggs from being damaged during the freezing/thawing process. The media system dehydrates eggs during egg freezing and rehydrates the egg during thawing, thereby minimizing the formation of ice crystals. The result is a solid cell that resembles glass.
Once an egg is thawed and rehydrated, fertilization is accomplished through ICSI (intracytoplasmic sperm injection). With ICSI, the embryologist injects a single sperm directly into an egg to fertilize it, thus overcoming any hardening of the egg’s outer membrane that would otherwise prevent fertilization.
Benefits of egg freezing
Egg freezing is an effective female fertility preservation method for three specific situations that put a woman’s reproductive abilities at risk:
- Women diagnosed with cancer but who have not begun chemotherapy or radiotherapy. Cancer treatment can be toxic to oocytes and can leave few, if any, viable eggs.
- Women undergoing fertility treatment with assisted reproductive technologies but for religious or personal reasons do not consider embryo freezing an option.
- Women who would like to preserve their future ability to have children, either because they do not yet have a partner, or for other personal or medical reasons.
In addition, cryopreservation in general seems to reduce the chances of premature birth, low birth weight and ante-partum hemorrhage, according to a meta review of 11 studies comparing outcomes of approximately 37,000 pregnancies using IVF that was done by researchers at the University of Aberdeen and Aberdeen Maternity Hospital.
Egg viability & age
A woman’s age plays a major role in achieving a successful pregnancy because as a woman gets older, the quality of her eggs diminishes. Female fertility peaks around age 27 then begins to decline, and by age 40, the chance of getting pregnant is less than 10 percent.
Women in their late 30s and older possess eggs that are less likely to form healthy, robust embryos, leading to lower pregnancy rates, an increase in the rate of birth defects, an increased risk of Down syndrome, and a greater risk of miscarriage.
However, a woman’s uterus and overall health status may continue to be strong and be able to carry a health pregnancy even into her late 40s. A woman who freezes her eggs while still in her fertile peak can effectively stop the effects of the “biological clock” on her eggs, saving them for future family planning.
Risks of egg freezing
In spite of apparently normal babies conceived through egg freezing, there are reasons to be cautious. Since egg freezing is a relatively new technique, the long term risks (if any) to a baby have not been established. We know that the mature egg is a very unique cell that can easily be damaged by the cryopreservation procedure. Some studies have shown that freezing may damage the structures vital to chromosomal separation in embryos.
Fortunately, as with most fertility treatments, abnormal embryos usually do not result in a live birth. To date, the risk of genetic disorders like Down syndrome are not known to be increased with egg freezing or IVF. Theoretically, a woman’s risk of Down syndrome is determined by the age she was when her eggs were frozen, not her age when the eggs are thawed.
Some clinics suggest a cutoff age of 50, the average age of menopause, for a woman to attempt pregnancy using her frozen eggs. After 50, pregnancy can be riskier to a woman’s health. Speak with a fertility specialist to determine the best course of action for your specific circumstances.