A woman’s fertility is considered to at its peak in her twenties, but for many women having a baby at this stage of life is not an option, and many are now using fertility preservation to delay the start of their families until their late 30s or even older.
Unfortunately, however, it can become harder for a woman to conceive as she gets older, with their being an associated increased risk of suffering from a miscarriage. This is because the number and quality of the eggs in the ovaries declines rapidly after the mid 30s.
The effects of these changes are best illustrated by the national IVF figures, provided by the HFEA’s published data, showing that the success of IVF declines with increasing age: for example, the live birth rate per cycle started for the under 35 years age group was over 30%, with this figure falling to 20% at 38 years of age and to less than 5% for over 45 years of age.
Furthermore, the success of an IVF cycle in an older woman using eggs donated from a younger woman, is dependent on the age of the donor. A ‘young’ egg is considered to be more fertile, with the resulting embryos having a better chance of implanting successfully.
Vitrification for fertility preservation
Vitrification allows eggs to be safely frozen without losing their viability, so that they can then be stored for later use. During fertility preservation, women will undergo ovarian stimulation and an egg collection like other IVF cycles, but instead of the eggs being combined with the sperm, the eggs are frozen in their unfertilised state.
The technology is relatively new, but the results are encouraging, with units around the world achieving a pregnancy rate of 25% with the use of frozen (vitrified) mature eggs. This compares favourably with the success rates for fresh IVF cycles, in patients of the same age. The number of babies born following these procedures is increasing all the time.
Declining fertility is due to the age of the eggs, and therefore, fertility preservation is most effective if a woman is young when her eggs are frozen. Nevertheless, it could have a place for women in their mid-30s or older who do not want to have a family just yet. If you feel that fertility preservation might be for you, you can learn more about what is involved below.
Putting your fertility on ice is very similar to the start of a standard IVF cycle. It involves ovarian stimulation followed by a procedure to remove the eggs. You can see a full patient journey here
The eggs are then carefully vitrified and stored in liquid nitrogen at -196°C. They can be kept under these conditions without deterioration, for an indeterminate length of time.
Thawing, insemination, incubation
When you decide that it is time to use these eggs, they will be thawed at the appropriate time of your menstrual cycle and injected with a single sperm using intracytoplasmic sperm injection (ICSI). The injected eggs are then placed into an incubator so that fertilisation can take place.
All being well, one or two successfully developed embryos will be transferred to your womb a few days later.
Objective statistics and expectations, using vitrification
These statistics are based on a single treatment cycle yielding a sufficient number of eggs to provide a reasonable chance of success. If you respond well to ovarian stimulation treatment, whereby 10 eggs are collected, we would expect approximately 8 of these, to be mature and suitable for freezing.
We would anticipate that all of them would survive the freezing and thawing processes successfully. Upon thawing, the eggs are then subjected to ICSI, with fertilisation being confirmed the next day. We can estimate that there would be approximately 6 viable embryos at this stage, if 8 mature eggs were retrieved. On average, depending upon the age of the egg at freezing, each of those viable embryos has a 15-30% chance of leading to a live birth.
Of course, there will be wide individual variation around each of these figures, but they do indicate the potential success of the treatment. Younger women could expect to produce more than 10 eggs, each of which would have a higher expectation of implantation than those of older women. Hence, the younger the woman at the stage of egg vitrification, the better the results that can be expected. The age of the woman at the stage of thawing and implantation has a negligible impact upon the end outcome.
To learn more about any of our services and fertility treatment options, or to book an appointment with one of our consultants, please contact us.