Cryopreservation (freezing) of Sperm and Embryos

Freezing your sperm and embryos is very common now. The process of freezing them is called vitrification. It appears that all can be frozen successfully for an indefinite period of time with no harm to them or any pregnancy that results from them. There are no increased risks of genetic problems in children born from frozen embryos or sperm. These children appear to be as normal as children who are conceived naturally.

Men who choose to freeze their sperm are those who would like to have their sperm available for use later in situations where they are concerned that they may no longer be able to produce sperm. This can be when they are suffering from cancer and/or cancer treatment or even undergoing surgery that may affect their reproductive status. Couples where the male partner travels a lot and would not be available to provide a semen sample when required during a treatment cycle, may wish to freeze sperm so that sperm is available when needed.

Embryos can also be frozen. These embryos have been created during an IVF cycle. It is very common to freeze excess embryos after an IVF cycle. There appears to be very little if no harm at all to embryos with the vitrification freezing process.

Fertility Preservation for Women (Egg Freezing)

Egg freezing first began in 1986. The method used in those days did not lead to good survival of the eggs when thawed. We can now successfully freeze and thaw eggs with the process of vitrification. Egg freezing is no longer considered experimental.

Many women may consider freezing their eggs. Patients with cancer may be offered the option of freezing their eggs if their treatment may compromise the future fertility potential of their ovaries and eggs. Women who are at a stage in their life where creating a pregnancy is not desirable may wish to freeze theirs eggs for use to create a pregnancy at a later time. Once frozen, eggs do not “age” and therefore maintain their potential to create a pregnancy that is equivalent to the potential that is related to the age of the woman at the time of freezing. Some women may wish to freeze their eggs with the goal of donating them to another women (most commonly a family member or a friend) again at a later date.

RCC offers the opportunity to freeze eggs.

Successful live birth with the use of the frozen eggs is dependent on the age of the eggs used for freezing; the older the patient the less likely the chance of a live birth when the eggs are thawed and embryos created. The younger the age of the woman who is freezing her eggs, the greater the chance of success of gaining a pregnancy with those eggs. Studies suggest that freezing eggs from women up to the age of 42 gives a viable chance for a pregnancy resulting from these eggs in the future but the younger the woman who has frozen the eggs, the better.

The more eggs that are frozen for use later the greater the chance that one will result in a pregnancy and live birth. The older the patient, the more eggs are recommended to be frozen. However, it the older patient who has more difficulty producing enough eggs for freezing. It is suggested that the best outcomes are achieved when 9 or more eggs are frozen. For women who are freezing eggs because of cancer treatment, the approach is to freeze as many or as few as are obtained through the stimulation process. The opportunity to repeat the process may be limited due to imminent cancer treatment that cannot be delayed.

The vast majority of eggs will survive the freezing process when thawed. This however, does not guarantee that they will become fertilized, develop and lead to a pregnancy. Many eggs are naturally abnormal and they tend to either not fertilize or have an increased chance of leading to a miscarriage. This is not related to the fact that they had been frozen. Babies created from frozen eggs appear to have the same chance of being normal as babies conceived through IVF.

Though it is not known how long eggs can remain frozen without any damage to them, it appears that they can remain frozen for a long time (years).

When a woman returns to use her eggs that have been frozen, they will be assessed and then provided with medications to prepare her body to receive a potential pregnancy. The eggs are then thawed, fertilized with sperm and the resulting embryo(s) are placed in the uterus to see if they will implant. Embryos that are created during this process but not placed in your uterus, can be frozen again without harm and thawed for use at a later time.