Egg freezing involves the collection and cryopreservation of eggs. Some common reasons a person may choose to freeze eggs include being single, above the age of 30 and aware that the fertility potential is declining or due to a medical conditions such as cancer. Family history may be another reason. It is a great option for women who are not in a position to try for a baby in the immediate future or whose fertility is at risk for medical reasons.
It is known that as people with ovaries advance in age the number of eggs in the ovaries declines and so too does the quality. Therefore, people who attempt to conceive at a later age may find it increasingly difficult to do so.
What is the ideal age to freeze eggs?
Age 25-30: Fertility at this age is usually excellent. From a scientific prospective this is the best time to freeze eggs as it could be most cost effective time however this is often not practical due to lifestyle and financial reasons.
Age 30-34: Early thirties is considered the best time for egg freezing. Quality of the eggs remains relatively high and there is a good chance that a reasonable number of eggs will be collected per cycle.
Age 35-37: Evidence shows that there’s a sharp decline in fertility at age 35. Women at this age require more eggs to be frozen to achieve comparable pregnancy rates. The number of eggs collected per cycle is lower and lower number of eggs survive the freeze thaw process.
Age 38-40: Many more eggs are needed to be frozen. Often treatment may require multiple cycles. Egg freezing for women in this age group does not guarantee pregnancy.
Age >40: At 40 years and over, a woman’s chance of getting pregnant naturally drops to around 5% each month. Egg freezing is not ideal at this age. Donor sperm is a viable option for women wanting to start a family on their own.
Similar to an IVF cycle, approximately 10 to 12 days of FSH injections are required to be taken to encourage the development of follicles in the ovaries. Under ultrasound guidance the eggs are collected around approximately day 14 under general anaesthetic.
Once the eggs have been collected the support cells around the eggs are removed. At this time the embryologists can determine whether the eggs are mature. Only mature eggs are suitable for freezing therefore not all the eggs retrieved may be frozen. Mature eggs are frozen by first exposing them to a cryo-protective solution and then freezing very rapidly using a process called vitrification.
Similar to freezing embryos, once the eggs are frozen, they are stable for an indefinite period. Thawing involves the quick warming of the egg to 37°C and the removal of the cryoprotective solution. After a short period of recovery, the eggs are then suitable for insemination, usually by injecting a single sperm into the egg. After fertilization, embryo culture is performed using standard procedures.
Is egg freezing successful?
Recent international research has indicated that, on a per thawed oocyte basis, the use of frozen eggs has the potential to give similar results as using freshly collected eggs which are used in an IVF cycle. Published results suggest a single pregnancy may be produced on average from about 10 -15 oocytes. This number is higher for people who's eggs were collected at a more advanced age.
Important factors that determine the ultimate success of having a baby from frozen eggs depends on the age when the eggs are frozen, the number of eggs that are stored and the quality of eggs that are retrieved. It is essential to note that sometimes patients may need multiple attempts at egg collection in order to achieve an adequate number to freeze. Some eggs may not be suitable for freezing. Some eggs may not survive the freezing and thawing process. Some eggs may not eventually fertilize and develop into normal embryos. Of the embryos that are transferred only some will result in a pregnancy and some pregnancies may miscarry.
Are there any risks?
The procedure is similar to egg collection during routine IVF however potential risks are
A small number of women have an excessive response to the fertility drugs and can develop ovarian hyperstimulation syndrome (OHSS).
Rare procedure related complications such as infection, vessel and visceral injuries.
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.
Current data does not support increase risk of malignancy with the drugs used.
Lastly, in most cases Medicare rebates apply to egg freezing for medical reasons only.