There is increasingly good evidence that pregnancy rates using frozen/thawed eggs are similar to pregnancy rates using fresh eggs in young women and egg freezing has become a viable option for women who wish to preserve their reproductive potential.
The first baby born using frozen eggs was in 1986 but success rates were so low at that time that egg freezing was largely abandoned. Advances in cryoprotectants, the introduction of intracytoplasmic sperm injection (ICSI) and freezing methods such as vitrification have transformed that picture.
Many women, for social, educational and financial reasons, often delay starting a family until their late thirties by which time the chance of conceiving is reduced and/or they find themselves with sub-fertility problems. It is well known that egg quality and quantity diminish as women get older and the success rates for pregnancy even from IVF treatment declines.
Egg freezing offers women the potential to freeze eggs at a time when such an intervention has a good chance of leading to a live birth, which is ideally at less than 35 years. However, whilst live birth rates from egg freezing decline with age, live birth rates have been recorded to occur as late as 42 from frozen eggs.
Success Rates of Egg Freezing:
There are limited good studies looking at live birth rates from frozen eggs. What information is available shows that approximately 90% of eggs survive the vitrification (freezing) and thawing process. Of those eggs that survive, approximately 70% will fertilise to produce embryos.
Clinical pregnancy rates are approximately 35% (dependent on the age of the women at the time of freezing. This will be lower for women more than 35years old).
Potential Risks of Egg Freezing:
There are no reported increased risks in chromosomal abnormalities, birth defects and developmental problems in children born as a result of egg freezing compared to the general population.
The Egg Freezing Process:
An egg freezing treatment cycle starts exactly the same way as an IVF treatment cycle. It requires the woman to take daily injections to stimulate the ovaries to produce a ‘good number’ of eggs. The number of eggs produced will depend upon the age of the woman and her ovarian reserve and the dose of drugs used for stimulation will be adjusted accordingly.
The stimulation process usually takes 12 to 14 days during which time 2 to 3 scans are required to assess the ovaries. An egg collection is performed on approximately days 14 to16 of the treatment and is performed under sedation and takes approximately 30 minutes to perform. The eggs are assessed in the laboratory and those eggs of correct maturity are frozen using a technique known as vitrification.
Side Effects of Egg Freezing:
The treatment can cause mild bloating but this usually settles within 5 days of the egg collection. Risks such as ovarian hyperstimulation syndrome seen in women undertaking IVF treatment is extremely low as embryos are not being replaced.
Prior to undertaking treatment a pelvic ultrasound is required to view the ovaries and check the antral follicle count which is used as an indicator of ovarian reserve. The accessibility of the ovaries to the egg collection process is also assessed.
Ovarian reserve is also assessed by an AMH test which is a blood test and can be taken at any time in the menstrual cycle.
Blood is also taken for screening for Hepatitis B surface antigen, Hepatitis B core antibody, HIV and Hepatitis C.
There are a number of forms that need to be completed as egg freezing is regulated in the UK by the Human Fertilisation and Embryology Authority (HFEA)
Costs of Egg Freezing:
- Initial consultation, pre-treatment scan and blood tests
- Stimulation process, egg retrieval and egg freezing
- Drugs for the stimulation
Total costs approximately: £5,000