Embryo cryopreservation is the process of freezing and storing embryos and is a part of most in vitro fertilization programs. The process is chosen for reasons as varied as providing an additional chance for pregnancy, or saving embryos in the face of certain medical treatments.

What is in vitro fertilization (IVF)?

Many women and their partners try for a long time to get pregnant, but can’t. Some may turn to the process of in vitro fertilization (IVF) to help them have a baby.

With IVF, a woman’s egg cells and a man’s sperm cells are put together in a dish in a special fluid in the laboratory. The new cell that is made when an egg cell and a sperm cell combine is called an embryo. The doctor then transfers the embryo into the woman’s uterus (womb). The embryo implants (attaches) to the wall of the uterus, where it develops and grows into a baby.

As part of the IVF process, the woman is given special drugs that cause her ovaries to release more egg cells than normal. The man also gives a high number of sperm cells. With many egg and sperm cells to work with, several embryos are often made. The doctor will transfer one to four embryos, based mainly on the woman’s age, into her uterus to lower the chances that she will have more than one baby. That means there may be some embryos left over.

What is Embryo?

In the in vitro fertilization treatment, after the mother passes through the egg collection process, the eggs of the candidate father are fertilized in the laboratory environment. As a result of this fertilization, a new cell with 46 chromosomes is formed to form the baby. The embryo is the first stage in which the cell division begins for the formation of the baby after the sperm fertilizes the egg. While the egg carries the DNA of a single mother, the embryo carries the DNA of the mother and father together.

What is embryo freezing?

The embryos obtained by fertilization of the eggs taken from the mother and the sperm taken from the father in the laboratory environment are subjected to special procedures for subsequent pregnancy experiments and this process is called embryo freezing.

What is embryo cryopreservation?

Embryo cryopreservation is the process of freezing and storing the extra embryos. The embryos are then thawed and used at a later time. Embryo cryopreservation is a vital part of most IVF programs.

What are the differences between embryo and egg freezing?

During egg and embryo freezing procedures, the ovaries are stimulated with hormonal needles and the eggs are collected on the ultrasound threshold. The medical treatments and processes so far are the same. Afterwards, the difference in egg-freezing is done by freezing the eggs directly, while embryo freezing is achieved by fertilization with sperm. In between days, solid and good quality ones are selected and frozen. Embryo freezing cannot be applied to unmarried single women because sperm is required.

When is embryo freezing done?

Frozen embryo transfer has become an alternative to fresh embryo transfer in recent years. Because, it is not possible to obtain a pregnancy with fresh embryo transfer, termination of miscarriage, or after the birth and termination of pregnancy, when it is desired to have a child again, embryos that are frozen according to the wishes of couples are thawed and placed in the mother’s womb and pregnancy can be provided again.

Why is embryo freezing done?

Following the application of fresh embryo transfer, the remaining non-transferred embryos of good quality that can be frozen can be stored and used for re-transfer in the future. Thanks to these frozen embryos, the expectant mother can be prepared for embryo transfer without using hormone needles and egg collection. Thus, a period that is much less costly and less stressful for the mother will be spent.

The most important factor is the age of the mother

The most important factor that determines the formation of embryos with the chance of freezing is the age of the mother. While this chance is 50% before 38 years and before, it decreases to 12% at 40 years and over. There are studies that have higher pregnancy rates in frozen embryo transfers because the cervix is exposed to more physiological hormone levels than fresh cycles. If the embryo quality is the same; The chances of success of the fresh embryo and the frozen embryo are the same.

How are frozen embryos stored?

The transfer process of embryos that have been frozen and stored for up to 5 years in accordance with the laws determined by the Ministry of Health is carried out during periods when the cervix is suitable to hold as in the case of fresh embryo transfers. Embryo freezing is performed by “vitrification” method. Embryos, development of 2,3,4,5. and 6 days. Embryos frozen with the consent of the family are kept in a tank with liquid nitrogen within -196 degrees where no biological activity occurs.

How to thaw the frozen embryo?

Embryos can maintain their viability at 90% after thawing. There is no difference between frozen and then thawed embryos and fresh embryos that occur in normal in vitro fertilization. In case of success after both applications, medically healthy babies are born.

What is the success rate of embryo freezing?

The quality of embryos to be frozen during the freezing process is very important. Since the embryos of the best quality will suffer the least damage from the freezing process, the viability rate after the frozen embryo is 75-90%, while the survival of poor quality embryos is very low (20-25%). Therefore, only good quality embryos are frozen.

When the results are taken from all over the world, pregnancy rates after frozen embryo transfer vary between 25-50%. These rates vary according to clinical and laboratory procedures, age of the patient, cause of infertility and viability rate per embryo.

Why is embryo cryopreservation done?

There are many reasons a man and woman might choose to freeze and store their embryos:

• They may feel it is a better option than having the extra embryos destroyed.
• It can provide another chance to get pregnant if the IVF process fails the first time. The couple will not have to go through IVF again.
• If the man and woman have a baby, they can use the embryos later to have a second baby.
• The woman can save embryos before she begins treatments, such as for cancer, that might reduce or eliminate her chances of getting pregnant.
• The embryos could be saved and given to someone else in a donor program.
• The embryos could be saved and donated for research.