I have come across this question many times before. If you do research on fertility clinics abroad, you will see that the donor egg success rates advertised seem to hover around the 50-60% mark. This is usually the clinical success rate, but you should check to be sure because it is possible that the chemical success rate is being reported (and this is usually higher).
This success rate usually relates to the pregnancy rate following embryo transfer. You could further drill down and ask the pregnancy rate per embryo transferred. This will be lower because clinics often transfer more than one embryo. It is also prudent to ask about how many cycles got to embryo transfer because obviously the fewer cycles there are, the less predictive are the results.
Why not give live birth rates? I think that for IVF clinics which treat many people from abroad, this particular statistic may be more difficult to report. Contacting everyone after their due date may be logistically a bit difficult.
So it can be difficult to compare like-with-like when it comes to pregnancy rate.
But back to the question – why do pregnancy rates seem higher abroad. Well a perceived increase in pregnancy rate in clinics abroad can be explained by the following:
1) The number of embryos transferred may be greater abroad than in the UK. There is a real push to promote single embryo transfer in the UK. Abroad, the average number of embryos transferred is usually about two. The result of this may lead to an increased pregnancy rate.
2) Blastocysts are routinely used for embryo transfer abroad and are usually included in the price advertised (this can be called extended culture). At this stage, the embryo has passed all of its milestones and is progressing in development. So transferring at this stage means that preimplantation development has successfully completed. Transferring embryos at this stage should lead to better success.
3) The egg donors will on the whole be younger than donors in the UK. Having a younger egg donor may mean that egg quality is superior. Although many women do donate here in the UK, it can tend to be women who are a little older – friends, family members. Women going through treatment themselves for infertility also donate eggs. However, if the cause of the infertility is unknown, this may lower the chance of success for the recipients of these eggs.
4) IVF clinics abroad can use “proven” donors a few times (in Spain six children can be born from the same donor -including her own). So the chances of success with each cycle using a proven donor may be higher.
I hope this has partly answered the question about IVF success rates abroad.