The chance of a live birth from frozen ‘vitrified’ eggs is similar to the chance from ‘fresh’ eggs which are usually used in IVF treatment. The two most important factors that determine the chance of having a baby from frozen eggs are your age when your 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.
The number of eggs available for freezing and their quality is important because in every step there is a risk that some are 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.
The following graph, published in the journal Human Reproduction in 2017, estimates the probability of a live birth according to how many mature eggs a woman freezes at various ages. The graph shows that a woman who freezes 10 eggs at the age of 44 has about an 8 per cent chance of having a baby, whereas a woman who freezes 10 eggs under the age of 35 has about a 70 per cent chance.
The method for freezing eggs varies between clinics but studies show that the most effective method for freezing eggs is a rapid method called ‘vitrification’.