After reviewing 5 years worth of data regarding its egg donation programmes CRM London has revealed some interesting trends specifically in relation to egg share donors. From 2007 to 2011 CRM London found that of those egg share donors who received free IVF treatment including free drug treatment, and donated half of their eggs to an anonymous recipient and kept the other half for their own IVF treatment, 42% have either delivered a baby, or are currently over 3 months pregnant. This was their chance of pregnancy for each treatment cycle. Some had several free treatment cycles and had a higher chance of pregnancy overall. This is from a group of 449 women who donated eggs and underwent fertility treatment in the London fertility clinic over the past 5 years.
It is when these results are compared with women of the same age, who were not donating eggs and keeping all the eggs for themselves that it becomes interesting. Of 804 women who did not donate eggs, a lower percentage of 38% are currently more than 3 months pregnant, or have delivered a baby. This shows that the egg sharers who have free IVF treatment and donate half of their eggs have better pregnancy results than IVF patients who pay for their treatment and use all of their eggs in treatment.
Why? It is most likely due to the fact that women who are accepted on the egg sharing programme have been screened to have high pregnancy potential based on blood tests and scans, whereas there are no selection criteria for self funded patients.
The research has also revealed that in recipients of donated eggs, 475 women had embryos resulting from donated eggs transferred at CRM London in this 5 year period. Of which, 44% have either delivered or are more than 3 months pregnant, showing that recipients have the most successful results of all, despite usually being of an older age group than the donors.
The trend can be accounted to 2 predominant factors. Firstly, the age of the donor determines the chances of pregnancy not the age of the recipient and secondly, both egg donors and patients having IVF treatment with their own eggs receive drugs to stimulate their ovaries to produce multiple eggs.
Treatment is therefore aimed at boosting the ovary. For recipients the ovaries are not stimulated at all and attention can be focused on improving the uterine factor to help embryos implant. It is also worth pointing out that these results are only based on pregnancies from fresh embryo transfer and do not include further pregnancies arising from the transfer of frozen embryos.
With the advent of paid egg donation it will be interesting to see whether the pregnancy rates are any different, particularly when paid egg donors who are not receiving any fertility treatment are considered. The stringent screening processes for paid donors and egg sharers should however, limit the variance in success rates.