What is the process of egg freezing?
While sperm and embryos have proven easy to freeze, the egg is the largest cell in the human body and contains a large amount of water – when frozen, ice crystals form that can destroy the cell. This necessitates dehydrating the egg and replacing the water with an ‘anti-freeze’ prior to freezing, in order to prevent ice crystal formation. This is done using cryoprotectants, which replace most of the water within the cell and inhibit the formation of ice crystals.
During the freezing process, the egg membrane can be modified, preventing fertilisation. When the eggs are thawed, a special fertilisation procedure is then performed by an embryologist, whereby sperm is injected directly into the egg with a needle rather than allowing sperm to penetrate naturally by placing it around the egg in a dish. This injection technique is called Intracytoplasmic Sperm Injection (ICSI) and is used in IVF.
Why would a woman opt for egg freezing?
The simple answer is to take advantage of the best egg quality and quantity in the prime reproductive years — a woman’s 20s and early 30s.
A woman is born with all of the eggs she will ever have, and over time they diminish in number and cellular quality. This decline explains why a woman in her 40s has only a five percent chance of becoming pregnant each month; her eggs are also more likely to develop abnormal chromosomes after the age of 45.
Basic fertility testing, including antral follicle counts and hormone and AMH blood testing, assesses a woman’s ovarian reserve. A clearer picture of egg quantity and ovarian function may lead a woman to opt for elective fertility preservation. Other reasons why a woman may choose egg freezing include:
1. If she would like to preserve her fertility until she’s ready to start a family. Today, we see many women delaying childbearing due to personal or medical reasons and then struggling to conceive in later years. Pregnancy rates from frozen eggs will depend on the woman’s age at the time she freezes her eggs, but will not be affected by the age at which she comes back to use them.
It is important to note that the chance of future pregnancy in women who are older than 38 at the time of freezing their eggs is likely to be lower than that seen for younger women. To date, there are few reports of pregnancies in women over 38 from frozen eggs, but this is mostly due to lower age cut-offs in egg freezing studies and the relatively low number of women who have come back to use their frozen eggs so far.
2. If she’s been diagnosed with cancer and has not yet begun chemotherapy or radiotherapy. In the short time that is available, stimulation of the ovaries can be undertaken safely and eggs can be preserved as significant damage to the ovarian follicles is expected after cancer treatment.
3. Those with religious or other reasons not to freeze embryos during in vitro fertilisation may find that egg freezing is a viable option.
How many eggs are needed to be stored to achieve a pregnancy?
Based on preliminary data from our own studies and those of others, egg thaw rates of 75% and fertilisation rates of 75% are anticipated in women up to 38 years of age. Thus, if 10 eggs are frozen, seven are expected to survive the thaw, and five to six are expected to fertilise and become embryos. Usually three to four embryos are transferred in women up to 38 years of age. We recommend that 10 eggs be stored for each pregnancy attempt, and most women of up to 38 years of age can expect to harvest 10 to 20 eggs per cycle.
Is egg freezing safe?
To date, approximately 5,000 babies have been born from frozen eggs. The largest published study – of over 900 such babies – showed no increased rate of birth defects when compared to the general population. Additionally, results from one study showed no increased rates of chromosomal defects between embryos derived from frozen eggs and those derived from fresh eggs. In 2014, a new study showed that pregnancy complications were not increased after egg freezing. There have also been over 300,000 children born worldwide from frozen embryos using primarily slow-freeze cryopreservation techniques, without an increase in birth defects.
Although this data is reassuring, it will take many years of further study to ensure that babies born from egg freezing technology have no higher rates of birth defects than those conceived via other means.
How long can the eggs remain frozen?
Based on scientific evidence, as well as clinical experience in achieving pregnancies with frozen embryos – in one case the embryo was frozen for 10 years – we are confident that long-term storage of frozen eggs does not result in any decrease in quality.
What does the process involve?
In order to retrieve eggs for freezing, a patient undergoes the same hormone injection process as in vitro fertilization. The only difference is that following egg retrieval the eggs are frozen for a period before they are thawed, fertilised and transferred to the uterus as embryos.
It takes approximately two to three weeks to complete the egg freezing cycle, which is consistent with the initial stages of the IVF process, including 10 to 14 days of hormone injections to stimulate the ovaries and ripen multiple eggs.
Once the eggs have adequately matured, they are removed with a needle that is carefully placed through the vagina under ultrasound guidance. This procedure is done under intravenous sedation and is not painful. The eggs are then immediately frozen. When the patient is ready to attempt pregnancy, which can be several years later, the eggs are thawed, injected with a single sperm to achieve fertilisation, and then transferred to the uterus as embryos.
What is the cost of egg freezing?
At the Fakih IVF Fertility Center the costs of egg freezing are identical to those of routine IVF. In general, it costs around Dh30,000 to undergo an egg freezing cycle in the UAE. This estimate includes all testing, monitoring, medications and egg freezing. The egg freezing fee includes the storage fee up to the end of the calendar year. There will be an additional annual storage fee beginning in January of the next full calendar year. The egg thaw, fertilisation and embryo transfer procedure costs roughly Dh18,000 which is payable at the time of thawing the eggs.
Information from Dr Monikaa Chawla, a reproductive endocrinologist and fertility specialist at Fakih IVF Fertility Center. For more information visit fakihivf.com
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