What is egg freezing?
Egg freezing can be offered to women who are facing significant decline in ovarian function, which may have an impact on their future fertility, as well as to cancer patients wishing to preserve their eggs prior to treatment. Egg freezing is also advised for young fertile patients wishing to preserve their eggs for future use (this is known as social egg freezing).
A woman’s fertility is predominantly dependent on the quality and quantity of her eggs. A healthy woman has a predetermined number of eggs, which is at its maximum before birth and declines rapidly throughout life. As egg numbers and in turn egg quality decline with age, chances of both natural conception and success through fertility treatment decrease significantly; especially in patients over 35, with this decline accelerating in those over 40 years of age.
Egg freezing allows women the option of freezing their eggs when younger (as opposed to using fresh low-quality eggs at an older age) thus offering them a better chance of a successful pregnancy in the future. The introduction of the vitrification technique has revolutionized the fertility preservation process as it minimizes ice crystal formation and therefore limits internal damage to the egg. Increasing worldwide data suggests that frozen eggs may be as effective in achieving pregnancy as fresh eggs and long-term data on pregnancy risks such as preterm labor or birth defects show no increase.
How many eggs should I freeze?
To maximize egg freezing as an ‘insurance’ policy, several stimulation cycles may be required. It is strongly recommended that women freeze eggs at as young an age as possible and aim for at least 15-20 eggs in storage. This would increase the chances of achieving a pregnancy if these eggs are used in the future. Most clinics worldwide offer three cycle packages.
Egg freezing is recommended if:
A patient will be undergoing any treatment (i.e. radiotherapy or chemotherapy) that may have an impact on ovarian reserve and future fertility.
A woman is 35 years of age and is not planning to start a family imminently.
How long can eggs be stored for?
Legislation varies from country to country. In the UK the law permits egg storage for up to 10 years. In cases where premature infertility can be confirmed (and certified by a medical practitioner), it is possible to store eggs up to 55 years.
Egg freezing process
Step 1: Stimulating the ovaries
Ovulation induction is the process of stimulating a woman’s ovaries to produce multiple eggs. Hormone injections (follicle stimulating hormone – FSH) must be administered subcutaneously (under the skin) daily for about two weeks. A second type of medication is also given in order to stop your ovaries from releasing these eggs (ovulating) before they are collected.
Step 2: Monitoring
Over a period of about two weeks whilst taking the stimulation drugs you will need to be scanned approximately 2-3 times in order to monitor the number and size of the follicles (each follicle will potentially include an egg). Sometimes blood tests will also be taken at the time of the scan to measure hormone levels. This will help the doctors decide when the eggs should be collected or whether the drugs need to be increased/decreased in order to optimize your treatment outcome. We can refer you to local clinics for the monitoring process if you are traveling abroad for treatment.
Step 3: Preparation for egg collection
When these eggs are ready (usually when the leading follicle reaches 17-22mm in size), preparations are made for the egg collection. This involves the administration of a hormone injection (human chorionic gonadotropin – hCG) approximately 36 hours prior to the planned egg collection. This triggers the eggs to mature making them ready for fertilization.
Step 4: Egg collection
Egg collection is performed under mild sedation using a minor vaginal procedure performed under ultrasound guidance during which the fluid in each of the developed follicles is collected. This fluid is simultaneously assessed by an embryologist and the presence/absence of an egg is confirmed.
Step 5: Egg freezing
After the eggs are collected, they are incubated and assessed for maturity. The cells surrounding the eggs are stripped away to identify which eggs are mature as only these can be frozen (vitrified).
Step 6: Future use
When the eggs are needed, they can be thawed and fertilized using the ICSI micromanipulation technique.