Some donors are non-anonymous, but most are anonymous, i.e. the donor conceived person does not know the true identity of the donor. Still, they may get the donor number from the fertility clinic. If that donor had donated before, then other donor conceived people with the same donor number are thus genetic half-siblings. In short, donor registries match people who type in the same donor number. Alternatively, if the donor number is not available, then known donor characteristics, e.g. hair, eye and skin color may be used in matching. Donors may also register, and therefore, donor registries may also match donors with their genetic children. The largest registry is the Donor Sibling Registry- with more than 25,000 members, the DSR has matched almost 7,000 donor conceived people with their egg and sperm donors, as well as with their half siblings. Alternate methods of providing an information link between the donor and recipient (both agreeing to stay registered on the DSR) are often provided for in the legal document (referred to as the "Egg Donor Agreement".) Embryo donation
An alternative to egg donation in some couples, especially those in whom the male partner cannot provide viable sperm, is embryo donation. Embryo donation is the use of embryos remaining after a couples IVF treatments have been completed, to another individual or couple, followed by the placement of those embryos into the recipient womans uterus, to facilitate pregnancy and childbirth. Embryo donation is more cost-effective than egg donation on a "per live birth" basis.
Due to the developmental implications of forming healthy parent-child relationships in early infancy, the finding that egg donor mothers were less sensitive and structuring towards their infants raises concern about attachment styles among egg donor families, and the impacts it may have on infants future socioemotional development. Telling the child
Most psychologists recommend being open and honest with children from an early age. Groups for donor conceived children make a strong case for the rights of children to have access to information about their genetic background. For donor conceived children who find out after a long period of secrecy, their main grief is usually not the fact that they are not the genetic child of the mother who raised (and, usually, gave birth to) them, but the fact that their parents lied to them, causing loss of trust. Furthermore, assuming that egg-donor conceived children have essentially the same reaction as sperm-donor conceived children, the overturning of ones lifelong understanding of who ones genetic parents were may cause a lasting sense of imbalance and loss of control. Telling the children that they were donor conceived is recommended, based on decades of experience with adoption (and more recent feedback from donor-conceived children) showing that not telling children is harmful to the parent-child relationship and to the child psychologically.