Embryo Cryopreservation

At 12:54pm on June 4,1986, at a Los Angeles area hospital, a couple named Monique and Gary gave birth to their son weighing in at 9 pounds 10ounces, delivered by cesarean section. This couple and their baby made US medical history. The baby was the first US frozen embryo baby to be born. The freezing of embryos is an extension of the IVF techniques that turned the world upside down in 1978 with the birth of Louise Brown in England, the very first "test-tube baby".

Now, here we are more than 25 years after the American birth and technology has provided surreal opportunities for couples to experience parenthood in heretofore impossible situations. The process used to preserve the embryo that gave Monique and Gary their son has been advanced and perfected over the years and the results have proven satisfactory to the lives of countless couples.

Why Use Embryo Cryopreservation?

Embryo cryopreservation is used in infertility programs primarily to freeze and store sperm, eggs, or to freeze so-called "leftover" embryos from an in vitro fertilization cycle. There are two methods of freezing embryos - slow freezing and vitrification (ultra-rapid freezing). The results with using vitrification are proving to be very good.

How Is Vitrification Different from Embryo Cryopreservation?

Vitrification, according to the dictionary is the process of converting something into a glass-like solid that is free of any crystal formation. Since ice crystals can be very damaging in the IVF process of using frozen embryos, the concept of using cryoprotectant and cooling the object until it hardens like glass without ice crystals forming is more than appealing. Vitrification in IVF allows for the freezing of embryos that weren't needed in the primary IVF procedure to be frozen with better survival rates after thawing. This also provides for higher pregnancy and live birth rates from frozen embryo transfer cycles.

Extra Embryos and Embryo Cryopreservation

The value to freezing surplus embryos is that couples who are undergoing IVF will have the advantage of having several cycles of IVF with eggs that were collected during one round of treatment. The fresh embryos can be used immediately and the frozen ones can be used at a later date, if needed.

IVF and other types of related treatments normally require the ovaries of the woman in treatment to be stimulated in order to produce several eggs over and above what would normally be produced. The clinic fertilizes all of the eggs harvested in order to select the most viable for fertilization and then, the most viable of the fertilized eggs for implantation. Not all embryos have the potential to develop properly, so the best are chosen from those that are developing. It is common for more than the one or two embryos necessary for implantation to be viable and have the ability to withstand freezing and thawing. By freezing these embryos, it provides an opportunity for another shot at pregnancy should the first fail, without having to go through the entire process again.


How Embryo Cryopreservation is Done

The freezing process occurs after the best embryos have been selected and those that will be used in immediate IVF treatment are taken. The rest of the selected embryos are placed in a cryoprotectant and inserted into a straw with identification markings placed on it. A witness oversees this procedure to ensure the information is correct. The straw is then placed into a freezer that lowers the temperature until -180C is reached. They are then placed into a tank of nitrogen and kept until needed. About 70% of embryos that are preserved in this fashion survive. Frozen embryos are stored for a period of five years at first. The period can be extended for another five years as long as the "owners" of the embryos agree. There is no known deterioration in the health of the embryo with time.

20-year-old Frozen Embryo - Healthy Baby Boy

To prove this point, in 2010 a healthy baby boy was born from a frozen embryo that was created in 1990 - 20 years earlier. The birth was reported in the online edition of the journal Fertility and Sterility. The 42-year-old mother of the baby began trying to get pregnant in 2000 and the couple had no success. She and her husband received embryos from a heterosexual couple who had themselves undergone IVF and that could had anonymously donated their leftover embryos after the woman successfully gave birth - in 1990.

Concerns About Embryo Cryopreservation

The concern that is rising in the field of assisted reproduction is the ethical and practical implications of keeping potential humans frozen for years and years. There are fights in divorce courts over frozen embryos. And then, there's the issue of what to do with the eggs, sperm and embryos that are created and not used. The question will be - How do we deal with this?

You can learn more about the process of freezing eggs and the process of IVF in this section.

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