Ask Our Obstetricians - Social Egg Freezing with Dr Min Kho

Some women who want a family choose to do so in their twenties and early thirties but research is showing us that more and more women are deciding to have their children later in life. According to data from Australian Mothers and Babies 2013, the number of women having their first babies at 35 years and older is sitting at 22%. Along with delaying childbirth past 35 comes the risk of decreased fertility and many women are looking at ways to “stop the clock” to preserve their fertility if childbirth is not on the horizon. Dr Min Kho is a consulting Obstetrician & Gynaecologist at North West Private Hospital. In this article she looks at the process of egg freezing, how it has advanced since its introduction, how it is carried out and its potential success rate.

How has egg freezing changed since it was first carried out in Australia?

Many advances have been made in the field of oocyte or egg freezing since the first pregnancy from a frozen egg was achieved in Australia in 1986. The advent of oocyte vitrification (fast freezing) in late 1990s has greatly improved the success rate of livebirths from frozen oocytes. In 2013, the American Society of Reproductive Medicine (ASRM) lifted the experimental label applied to oocyte freezing, following four randomised trials suggesting that IVF using vitrified-warmed oocytes could produce similar pregnancy rates compared to IVF from fresh oocytes.

What is involved in the process for the patient?

In order for women to freeze their eggs, they first have to undergo a cycle of controlled ovarian stimulation which involves up to two weeks of hormonal injections. A transvaginal aspiration of the oocytes is then performed to retrieve the eggs. The oocytes then undergo vitrification in the freezing process and are stored for potential future use. Once the eggs are frozen their biological age is locked in which is why women in their 30s may consider this process to preserve their fertility for later in life when they want to pursue having a family.

How many eggs should a patient freeze to have a reasonable chance at a successful pregnancy in the future?

It really depends on the age of the woman when she freezes her eggs. The average livebirth per oocyte rate is 6-7% so in order to have a good chance of having at least one livebirth, it is recommended that women who are less than 38 years of age freeze 15-20 eggs to improve the chance of having at least one child. However, women who are between 38-40 years of age should have 25-30 eggs frozen because they tend to have lower quality eggs. This would generally mean that they might need to undergo several cycles of ovarian stimulation to achieve that number.

From that data it seems that taking an “earlier the better” approach to making the decision would be advisable?

Clearly, the younger a woman freezes her eggs, the better the quality and quantity of her eggs. However, it’s not a decision to be taken lightly - it is a medical procedure and does come with significant costs attached. When a woman should consider egg freezing depends on factors such as her AMH (Anti-Mullerian Hormone) test results, the size of the family she wants to have and other gynaecological factors that contribute to her fertility.

So it’s important that patients consider many factors before they take this path?

Absolutely. Patients need to be clear that there is never a guarantee that egg freezing will totally preserve their fertility and after going through the process they still may not achieve a successful pregnancy. If having a child or children is something that’s very important to them it’s crucial that they understand this to avoid being disappointed later when it’s too late.

References:

Stoop D, Cobo A, Silber S. Fertility preservation for age-related fertility decline Lancet. 2014 Oct 4;384(9950):1311-9.

Six years' experience in ovum donation using vitrified oocytes: report of cumulative outcomes, impact of storage time, and development of a predictive model for oocyte survival rate. Cobo A, Garrido N, Pellicer A, Remohí J.Fertil Steril. 2015 Dec;104(6):1426-34.e1-8.