Egg freezing: Everything you need to know about the process

Freezing eggs to preserve fertility is a process that has become increasingly common in recent years.

 A woman checks an ovulation test (photo credit: INGIMAGE)
A woman checks an ovulation test
(photo credit: INGIMAGE)

Fertility preservation is a very topical issue today, but until a decade ago it wasn’t. 

In fact, only about 10 years ago, a law was passed that allows the preservation of fertility for non-medical reasons for women between the ages of 30 and 41. Why is it actually recommended to perform fertility preservation in one’s early 30s, what does the process include and what are its chances of success?

The important thing to remember is that the average chance of getting pregnant and giving birth by age 37 is about 30%, beyond the age of 40, the chance is only around 10%, and beyond the age of 42 it’s down to single digits. 

The older the eggs, the much lower the chance of getting pregnant, and there's also an increase in cases of miscarriages and chromosomal abnormalities in the fetus due to an older egg. Or in simple words: The decision to preserve eggs for women can be significant for them and increases the chance of having a healthy baby at a later age.

Why should women freeze eggs?

The reasons for preserving fertility are divided into two main reasons. The first is a medical cause, mainly due to cancers that require combined treatment of chemotherapy, radiation or surgery in the pelvic area, which may cause cessation of ovarian activity and ovulation. In these cases a fertility preservation procedure should be performed as soon as possible by freezing eggs or even sections of ovarian tissue for future use.

It’s important to note that in recent years it’s been possible to preserve fertility for medical reasons, funded by government-run health clinics, for women at risk of a rapid and significant decrease in ovarian egg reserves depending on the medical history or test results which assess the quality of the ovarian follicles.

The second reason is the preservation of social fertility. In this option, the intention is to freeze fertilized (fetal) or unfertilized eggs from a healthy woman who currently isn’t planning a pregnancy. Indeed, in recent years women have tended to postpone family planning for a later period in their lives, mainly in order to achieve self-fulfillment in terms of studies, career, travel and financial independence.

Which procedure is used to perform fertility preservation?

Since only one egg is naturally ovulated each month, in the preservation process the goal is to freeze as many eggs as possible in order to increase the chance that pregnancy will occur at the appropriate time. For this purpose, a treatment is performed in which hormonal stimulation is given in the form of daily injections from the beginning of the cycle for an average of 10 days, in order to develop a large number of follicles, which are actually the shell inside which the egg is located. Simultaneously with injections, hormonal blood tests and ultrasound tests are performed to monitor the number of follicles and their ripeness, until the appropriate time for the extraction of the eggs.

In this treatment, not every follicle contains an egg and therefore the final number of eggs will be known only after the extraction is performed. Hormonal stimulation causes a phenomenon called ovarian hyperstimulation that results from the amount of follicles and hormone levels they produce. Also, ovaries that contain several follicles compared to a single follicle in a natural cycle, are larger and can cause a feeling of bloating in the abdomen that is painful. These symptoms usually go away several days after the eggs are extracted.

How are eggs extracted from the follicles?

The ovulation procedure is performed under a short general anesthesia that lasts about 20-30 minutes. The operation is performed through inserting a needle into the vagina, while continuously monitoring with ultrasound and real-time information about the position of the needle during the entire extraction. In the operation, the follicles are punctured, and the fluid drawn from them is sent to a lab and checked for the presence of eggs. As mentioned, not every follicle contains an egg and not every egg is ripe and usable. Therefore the final number of eggs may be smaller than the number of follicles seen on ultrasound.

After the procedure, there may be slight vaginal bleeding and abdominal pain, which respond to treatment with fluids and painkillers. Usually after about an hour to two hours of supervision, you can be discharged from the unit and after a few days of rest, return to normal activities.

How to choose between freezing fertilized or unfertilized eggs?

Freezing unfertilized eggs

Women usually decide on this option when they don’t have a partner or when there is a reluctance to use sperm donation. The disadvantage of this procedure is that after years when you want to use the frozen eggs and the eggs have survived thawing, they have to go through a fertilization procedure. Not all eggs survive the freezing and thawing and not every egg is fertilized properly, so usually the number of suitable embryos is less than the frozen eggs.

On the other hand, the main advantage is that for unmarried women, freezing an unfertilized egg and not an embryo allows fertilization with the sperm of a future partner.

Freezing fertilized eggs

Egg fertilization is done by the partner's sperm, or from a sperm donation. The disadvantage of this procedure is that freezing fertilized eggs (embryos), determines the genetic component of the sperm in the fetus and prevents the possibility of future use of fertilizing the eggs with the sperm of a future mate. But in this procedure, the advantage is great because when a fertilized egg is frozen, it’s unnecessary to fertilize it with sperm since there are already embryos. The chances of survival of a fetus (fertilized egg) are slightly higher than an unfertilized egg and therefore no further procedure with sperm for fertilization is necessary.

In practice, most of the thawed embryos can be used without further intermediate procedure of fertilization.

What are the chances of success by age?

The most important factor influencing the chances of reaching the birth of a living and healthy child is the age of the woman at the time of egg freezing. The older the woman, the lower the quality and quantity of eggs and the less likely she is to become pregnant - that is between 10% and 30% depending on the age and quality of the eggs extracted. In practice, a frozen egg of a 35-year-old woman is better than a fresh egg of a woman at age 40.  In this age group, the implantation of fresh embryos also involves a decrease in the success rate. Today, the law allows for the freezing of up to 20 eggs or up to four extraction cycles, whichever is earlier.

These days, the Israeli Fertility Association recommends freezing from a younger age and a higher number of eggs. Doctors tend to recommend to women who have given birth after prolonged fertility treatments with poor ovarian reserve to consider fertility preservation even at a young age, in order to avoid difficulties with conception with their own eggs in the future. 

Remember that the fertility preservation procedure is an option to achieve pregnancy with your own eggs at the appropriate time. Not in every case where fertility preservation is done will pregnancy happen. Therefore, the sooner the better

Dr. Arik Kahana is the director of the In vitro fertilization unit at Assuta Hospital Rishon Lezion. This article was originally published by The Jerusalem Post's sister website, Walla!