Egg freezing

A woman’s chance of having a baby decreases with age – her most fertile years are in her early to mid-twenties, after which her fertility begins to decline. This decline speeds up after the age of 35.

Modern reproductive technology enables women to freeze and store their eggs. Some women do this for medical (health) reasons – for example because they want to preserve their fertility before undergoing cancer treatment, or because they are at risk of premature menopause.

Other women freeze their eggs for personal and social reasons to increase their chance of having a baby later in life – for example if they have not yet found the right partner, or because they are not ready to start having a family for career or financial reasons.

The most effective method for freezing eggs is a rapid method called ‘vitrification’.

Steps involved in egg freezing

There are several steps involved in the egg freezing process.

• Step 1. Your doctor will explain the process involved, including the risks and your chance of success. Fertility clinics should also offer women who consider egg freezing the opportunity to discuss the process and any concerns they may have with a specialist counsellor.
• Step 2. You will be screened for infectious diseases, including HIV and Hepatitis B and C.
• Step 3. You will be given a course of fertility drugs to stimulate your ovaries. The development of follicles (fluid filled sacs containing eggs) will be monitored with ultrasound examinations and blood tests.
• Step 4. When the eggs are mature they will be retrieved in an ultrasound-guided procedure while you are under light anaesthetic.
• Step 5. Your eggs will then be frozen and stored in liquid nitrogen at the fertility clinic.

When you are ready to become pregnant, your eggs will be thawed and fertilised with your partner’s or a donor’s sperm. If healthy embryos develop, one will be transferred to your uterus and any remaining embryos can be frozen for later use.

Egg storage

Biologically, eggs can be stored indefinitely. Laws about how long eggs can be stored vary between states, but often applications can be made for an extension to this time. Inform the clinic if you change your address so that you can be contacted if your eggs’ storage time limit is approaching.

Success rates from egg freezing

The chance of a live birth is similar for vitrified (frozen) and ‘fresh’ eggs used in IVF treatment. The two most important factors that determine the chance of having a baby from frozen eggs are your age when the eggs are frozen and the number of eggs that are stored.

The number and quality of the eggs that develop when the ovaries are stimulated decline with increasing age. A woman in her early thirties might have 15–20 eggs available for freezing after the hormone stimulation but for women in their late thirties and early forties the number is usually much lower. Also, as women age they are more likely to have eggs with chromosomal abnormalities such as Down syndrome.

It is estimated that to have a reasonable (70 per cent) chance of having a baby from frozen eggs, a woman who is 35 years or younger when she freezes her eggs needs to store 10 eggs. This increases to 20 eggs for a woman aged 38 years and as many as 35 eggs for a woman aged 40.

The number of eggs available for freezing, and their quality, is important because in every step there is a risk that some will be lost. Of the eggs that are retrieved, some may not be suitable for freezing, some may not survive the freezing and thawing processes, and some may not fertilise or develop into normal embryos. Of the embryos that are transferred, only some will result in a pregnancy, and some pregnancies miscarry.

Risks associated with egg freezing

A small proportion of women have an excessive response to the fertility drugs that are used to stimulate the ovaries. In rare cases this causes ovarian hyperstimulation syndrome (OHSS), a potentially serious condition. Bleeding and infection are very rare complications of the egg retrieval procedure.

Egg freezing is still a relatively new technique and the long-term health of babies born as a result is not known. However, it is reassuring that their health at birth appears to be similar to that of other children.

Costs of egg freezing

The cost of egg freezing varies between clinics. In most cases a Medicare rebate is only available for egg freezing for medical reasons, which means that women who freeze their eggs for personal reasons have considerable out-of-pocket expenses.

Clinics usually charge for the management of the stimulation, the drugs used to stimulate the ovaries, the egg collection procedure, and the freezing and storage of the eggs. Medicare does not cover the storage of frozen eggs, regardless of whether they are stored for medical or other reasons. There will also be costs involved when using the eggs to conceive.

Important questions to ask your doctor about egg freezing

A study of fertility clinics in the US found that the information about egg freezing on clinic websites was not always helpful. It is important that you are well-informed about all aspects of egg freezing before you decide to go ahead with treatment.

If you are thinking about freezing your eggs, here are some questions you can ask your doctor:

• Does the clinic uses vitrification, the most effective method, to freeze eggs?
• What’s the clinic’s success rate for egg freezing? (The best way to frame this question is by asking how many eggs have been thawed and how many live births have resulted from these.)
• What is your chance of having a baby from frozen eggs, considering your age?
• How many eggs do you need to store to have a reasonable chance of having a baby?
• What is the approximate total cost, bearing in mind that more than one stimulation and egg retrieval procedure may be needed to produce enough eggs.

Where to get help

• Your GP (doctor)
• Your obstetrician
• Victorian Assisted Reproductive Treatment Authority (VARTA) Tel. (03) 8601 5250