Among those who undergo a fertility treatment where donor eggs or sperm are used, it is generally accepted that success rates will be higher if compared to IVF cycles where own gametes (i.e. eggs and spermatozoa) are used. This belief derives from the fact that, when it comes to gamete donation, candidates are young, healthy people, free from any genetic abnormality or fertility issue.
Even though many factors may have an influence when trying to conceive, gametes play a major role in this process, hence the overall increase of donor gamete success rates.
It is important to keep in mind that the success rates provided hereunder have been obtained from an average between the results of various Spanish fertility clinics. That is the reason why finding fertility clinics with higher or lower rates is also possible.
Egg donor cycle
Reproductive success refers to the achievement of a live birth and not to pregnancy rates. However, it is not uncommon to find pregnancy rates based upon the latter parameter instead of the former.
This is the reason why, whenever we are talking about ART success rates, we must determine on the basis of which factors are we calculating how likely is our fertility treatment to succeed.
When donor eggs are used, in vitro fertilization (IVF) is the most commonly used assisted reproduction technique, either the conventional type or by means of ICSI (intracytoplasmic sperm injection), which stands for an advanced sort of IVF.
Pregnancy rates per embryo transfer rise to 56% approximately for egg donation cycles. As for birth rates or, more precisely, live birth rates per transfer, they usually reach 36.4% according to a study conducted by the Spanish Fertility Society (known in Spanish as SEF), in which a total amount of 164 fertility centers participated.
These figures refer to fresh donor eggs. If, conversely, it is a case of frozen donor eggs, where embryos develop from donor eggs that have previously undergone a freezing-thawing process, success rates may experience a minor variation:
- Pregnancy rate per transfer: 39.7%
- Live birth rate per transfer: 24.7%
This study does not explicitly mention whether the semen used was obtained from a donor or from the patient's partner. The recipient's age is neither taken into consideration even though it can have some influence on the final outcome in spite of not being a major issue.
When talking about sperm donation, it is important to keep in mind that two different assisted reproduction techniques can be used:
- Artificial insemination: It is the insertion of semen in the female's uterus by means of a cannula. In this case, only own eggs can be used, that is to say, from the mother-to-be.
- In vitro fertilization: In this case, either donor eggs (double-donor IVF) or own eggs can be used, previously obtained through follicular puncture. Then, they can be fertilized either via conventional IVF or ICSI.
As for sperm donation, the study conducted by the SEF makes no distinction between both fertility treatments and does not mention whether the eggs subject to study were obtained from a donor or from the patient herself. Thus, although it shows a birth rate per transfer that reaches 26.6% for sperm donation cycles, it should be understood as a general value, which makes it rather unrepresentative.
Regarding double-donor IVF, embryo quality may be higher in this case. This is due to the fact that embryos have been created from "strong" eggs and sperm, something that increases the chances of achieving success a priori. Nonetheless, this might be subjected to other factors such as the recipient's age, uterine receptivity, the characteristics of the uterus, embryo development, etc.
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