Faced with warnings from experts about the sharp decline in fertility among women in their mid-30s, more and more women are considering egg freezing as an "insurance" against age-related infertility.
Recent figures released by the Human Fertilization and Embryo Authority (HFEA) confirm that egg freezing is the fastest growing form of fertility treatment in the UK. The intake increased by 10% last year.
But what happens when women want to go back to the clinic to start families with their frozen eggs? Our latest research shows for the first time how many percent of them return to this "safety net" and how many percent manage to become mothers.
We analyzed data from two of the largest fertility clinics in London. We have attached information on all women who have frozen their eggs and on all women who used their eggs for conception between 2008 and 2017.
During this ten-year period, 129 women – about a fifth of all women who had their eggs frozen in the clinic – returned to use them. Of these women, just over a third (36%) had originally frozen their eggs for so-called "social" reasons (for example, due to concerns about reproductive aging). The remaining two thirds (64%) had their eggs frozen for various clinical reasons (as part of their IVF treatment to "stack" eggs or because no sperm sample was available on the day of egg retrieval).
The overall success rate was 21%, which means that only one in five women using their frozen eggs became the mother of these eggs. For social freezers, this figure was even lower at 17%. It is important to note, however, that another 26% of those who tried, but were unsuccessful, still had eggs or embryos in their stock, which hopefully could lead to future births.
The age of the women who freezed eggs was between 25 and 45 years, with an average of 37 years. Almost all women (98%) who had their eggs frozen for social reasons were single when the eggs were frozen. They returned to the clinic to thaw their eggs after about five years, with an average age of 43 years.
Although most women who freeze their eggs for social reasons say that their main motivation is to "gain time" to find a partner to have a family with, almost half of the women were after theirs Return unmarried to use their eggs. As a result, 48% used donor sperm to fertilize their eggs and opted for single motherhood instead of waiting longer to find a partner.
Like Ali, whose twins were born to Molly and Monty with their frozen, thawed eggs and donor sperm, she froze her eggs first, hoping to find someone with whom she could have a family. But over the years she said:
I started thinking about motherhood alone. I thought that I would be a good mother and knew that I would always regret if I did not try to have children with my frozen eggs. I will always be grateful to the donor for giving me my children.
Ali's story is heartwarming, especially when you see her beautiful five-year-old twins. But it is also a story of motherhood against adversity.
With current rates of success, most women who freeze their eggs will not be as happy as Ali, since egg freezing is not guaranteed. Both the number of frozen eggs and the age of the woman during freezing are factors that influence the probability of success, but there is also a chance factor, as with all fertility treatments.
Most women who have frozen their eggs have not tried to use them. It is likely that many will imagine the natural way without having to return to the clinic. Others may change their minds about children or for some reason decide to discard their eggs without using them. But some will simply wait for the right circumstances.
In the United Kingdom, eggs that have been frozen for social reasons can be stored for up to ten years (up to 55 years for medical reasons). Therefore, we do not have conclusive data on what decisions women make after freezing eggs until they meet them. Storage period has expired. It is likely that more women, especially those who have frozen their eggs in recent years, will try to use them in the future. The more women return to the clinics, the more studies can and should be done. However, by then, our data provides the most comprehensive insight available and should help women make more informed decisions.
Ali notes that although she believes that freezing eggs has given her an "amazing opportunity," she did not realize how hard it would be to get pregnant until she came back to use her eggs. "It took all the 27 eggs I had frozen to have my twins, so it was a close call," she says. "I almost started to panic!"
I know that freezing eggs may be a positive option for some women, and I strongly believe that all women should be helped to make the reproductive choices that suit them best. However, I think we need to be clear about how likely it is that this technology will lead to the future of motherhood.