Embryo donation is a form of fertility treatment. IVF patients who have embryos they do not want to use themselves can donate them to other couples who have been unable to concieve. They are given to couples who require both egg and sperm donation. The embryos can be used at the same time as the other couples IVF cycle or the embryos can be frozen and used at a later date. Frozen embryos can also be transported anywhere in the world. Once the embryo has been thawed they are placed into the womens uterus. Some fertility centres have much higher success rates than other. Success rates are very dependant on the programme that is used to freeze the embryos. Other variables include the age of the woman, the ‘quality’ and number of the embryos and how developed the embryo is when it is frozen.