How Are Eggs Frozen?

March 29, 2018

As the clock ticks by, the fertility of a woman decreases considerably. Just like every other organ, the ovaries too, age with time. By the time, a woman turns thirty-five, she has lost approximately a thousand eggs, as a result of her menstrual cycle each month. Roughly, around forty, she has only ten percent of her ovum intact. But, these eggs are usually of a poor quality. This might result in failed attempts of reproduction. Moreover, there are high chances of conceiving an unhealthy baby or giving birth to a baby with potential chromosomal abnormalities.

Thus, it might be a good decision for a woman to freeze her eggs while she is at her fertile best. This will ensure the probabilities of giving birth to a healthy baby in future. It also is a good resort for women who considering on having their ovaries removed due to medical reasons.

Generally, two methods of freezing are widely practised:

1. Slow Freezing

2. Vitrification


Slow freezing is the most commonly used method of freezing eggs. It is done by adding cryoprotectants to the egg. Here, cryoprotectant is the anti-freezing agent which prevents the formation of ice crystals. The addition of cryoprotectant stops the biological mechanism of the cell, hence, ensuring its storage for a long, long time. Although, the cryoprotectant prevents any osmotic damage to the cell, it might have a poisonous effect on the cell. The process of slow freezing stretches over two hours. The freezing is gradual. Although the process is pretty simple technically, there are thirty percent chances of cell loss. The process of slow freezing can be done on more than one cell at a time. So, if the first chance at conception is successful, the process can be repeated if the desire arises for a second pregnancy. However, one of the biggest drawbacks of slow freezing is that it cannot be performed on non-inseminated cells. Simply put, it cannot be used by females to ensure their future fertility if they do not have a partner in the present. It acts as a major disadvantage since many females look consider freezing as a lifestyle measure, too.


The vitrification of eggs is an ultra-rapid process. The whole process consumes five to ten minutes, in total. Before the procedure begins, the eggs are obtained from the body of the female. First, the dehydration of eggs take place by exposing them high concentrations to cryoprotectants. Then, the eggs are loaded with tiny storage devices. Lastly, the eggs are cooled rapidly. In the process of vitrification, the eggs are hardened but ice crystals are formed. The cryoprotectants used during the process, avoid any breakages in the cellular membrane.

When a patient desires pregnancy, the process of vitrification is reversed. The eggs are warmed both at the temperature and in an incubator. They are rehydrated and placed inside the uterus of the female immediately. After the eggs are in the uterus, they can be injected with sperm, three to four hours later.

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