Embryo freezing: What is the process and who benefits?

Embryo freezing is a modern science miracle and has been helping many couples all over the world in realizing their dream of having a child. A woman has all the eggs at birth, and they are stored in the ovaries. As you get older, your eggs will also get older. Fertility will decline with age, especially after 35 years of age, because the number and quality of eggs will decrease. From puberty to menopause, one egg is sent from the ovary to the uterus every month. When the egg combines with the sperm in the uterus, it becomes pregnant. Simply put, Embryo freezing allows people to store embryos for later use. Unfertilized eggs are also stored, which can be later fertilized when the female is ready to have children. Do you know that it was in 1980 that the first successful pregnancy via frozen embryos occurred? We at ZIVA fertility center, have years of experience in handling frozen embryos. In this blog, we would like to give you all the information about the process of embryo freezing and how it benefits you?

Understanding Embryo Freezing

Reasons for embryo freezing 

We have listed here the most common reasons:-

  • Planning for pregnancy in future and want to make sure that healthy embryos are available at the time.
  • Before undergoing cancer treatments like chemotherapy or radiation. 
  • Embryo donation is also becoming popular, a reason for freezing.
  • Medical research or training purposes.

Process of Embryo freezing

Hormones and other medications are given to stimulate the production of potentially fertile eggs. Then the eggs are extracted using an ultrasound machine, which can either be fertilized or frozen.

After successful fertilization, at least one healthy embryo is developed. If the fertilization results in multiple embryos, the doctor can freeze and preserve the embryos.

How is embryo freezing done?

During an IVF process, more than one healthy embryo is formed so couples usually freeze the additional embryos. These extra embryos are later thawed whenever the couple wants to have another child. The biggest challenge is the water within the cells which can easily freeze, resulting in crystals formation and cell bursting.


To prevent crystal formation and cell bursting we use a procedure called cryopreservation. The name is derived from the substance cryoprotectant used in the process. The water in the cells is replaced with this cryoprotectant. The embryos are incubated in increasing levels of cryoprotectant before freezing them. Once all the water is replaced the doctor cools the embryo to its preservation state. There are two methods of freezing:- 

Slow freezing: The embryos are placed in sealed tubes and the temperature is slowly lowered. This method prevents embryo cell ageing and reduces the risk of damage. Though beneficial it is a time taking process and requires expensive machinery. The success of reviving the embryos through this process is less compared to vitrification. This is an older technology used when embryo freezing started.

Vitrification: In vitrification, the cryoprotected embryos are frozen so quickly that the water molecules inside the cell have no time to form ice crystals. The embryos are protected and their survival rate during thawing also is high.

The embryos are frozen using any one of the above freezing methods and later stored in liquid nitrogen. The survival of the embryo on thawing is almost 99% and this is the latest advanced technology.

Success rates of thawing frozen embryos

Cryopreserved embryos have a relatively high success rate during thawing. Research suggests that women who underwent IVF with thawed embryos delivered healthy babies. According to a comparative study published in 2016, babies born after cryopreservation had no developmental abnormalities. Embryos frozen via vitrification had better survival, both at the freezing stage and during thawing.

Side effects of embryo freezing

The female experiences any complications or side effects of embryo freezing usually occur when the doctor extracts the eggs. Common side effects of extraction tend to be mild and temporary. They include:

  • Cramping or bloating
  • Feeling full
  • Bleeding
  • Changes in vaginal discharge
  • Infection
  • Overstimulation of the ovaries

How long can embryos stay frozen?

A properly frozen embryo is viable for any length of time since embryos remain in sealed containers at temperatures of -321ºF. And at such freezing temperatures no biological processes, such as ageing, can occur. Each country has their regulations regarding the length of time for embryo storage. The couple should know that both freezing and storing embryos is expensive.

At ZIVA fertility centers, we personally validate each and every case. We will understand your reasons for Embryo Freezing and usually make all the necessary arrangements. We are also fully experienced to handle whenever you are ready to have children. Please contact +91 91000 02737 or +91 93474 06900 to consult our fertility specialist. E-mail us at info@zivafertility.com