a 2002 study, egg donations had a 38% success rate in cases of women past their reproductive years. recipient and donor motivation intended parent motivation women may resort to egg donation because their ovaries may not be able to produce a substantial number of viable eggs. women may experience premature ovarian failure and stop producing viable eggs during their reproductive years. some women may be born without ovaries. ovaries damaged by chemotherapy or radiotherapy may also no longer produce healthy eggs. older women with diminished ovarian reserves or older women who are going through menopause could also become pregnant with egg donation. women who produce healthy eggs may also elect to use a donor egg so they will not pass on genetic diseases. donor motivation an egg donor may be motivated to donate eggs for altruistic reasons. a survey of 80 american women showed that 30% were motivated by altruism alone, another 20% were attracted only by monetary compensation, while 40% of donors were motivated by both reasons. the same study found that 45% of egg donors were students the first time they donated and averaged $4,000 for each donation. although the donors may be motivated by both monetary and altruistic reasons, egg agencies desire and prefer to choose donors that are strictly providing eggs for altruistic reasons. the european union limits any financial compensation for donors to at most $1500. in some countries, most notably spain and cyprus, this has limited donors to the poorest segments of society. in the united states, donors are paid regardless of how many eggs she produces. a donor's compensation may increase for each additional time she provides eggs, especially if the donor's eggs have a history of reliably resulting in the recipient becoming pregnant. in the united states, egg-broker agencies are known for advertising to college students who are more likely to be in financial situations that motivate them to participate for the financial compensation. it is not unusual for one student to donate many times. often, this is done without consideration of potential long-term health consequences. such a student is arguably not making the decision to donate her eggs autonomously due to her unfavorable financial situation. risks egg donor the procedures for the donor and the medication given to her are identical to the procedures and medications used in autologous ivf (i.e., ivf on patients who are using their own eggs). the egg donor thus has the same risk of complications from ivf as an autologous ivf patient would, such as bleeding from the oocyte recovery procedure and reactions to the hormones used to induce hyperovulation (producing more than one egg), including ovarian hyperstimulation syndrome (ohss) and, rarely, liver failure. according to jansen and tucker, writing in the same assisted reproductive technologies textbook referenced above, the risk of ohss varies with the clinic administering the hormones, from 6.6 to 8.4% of cycles, half of them "severe". the most severe form of ohss is life-threatening. recent studies have found that donors were at less risk of ohss when the final maturation of oocytes was induced by gnrh agonist than with recombinant hcg. both hormones were comparable in the number of mature oocytes produced and fertilization rates. a larger study in the netherlands found 10 documented cases of deaths from ivf, with a rate of 1:10,000. "all of these patients were treated with gnrh agonists and none of these cases have been published in the scientific literature." the long-term effect of egg donation on donors has not been well studied, but because the same medications and procedures are used, it is likely similar to the long-term effects (if any) of ivf on patients using their own eggs. the evidence of increased cancer risk is equivocal; some studies have found a slightly increased risk, particularly for those with a family history of breast cancer, while other studies have found no such risk or even a slightly reduced risk in most patients. 1 in 5 women report psychological effects—which may be positive or negative—from donating their eggs, and two-thirds of egg donors were happy with the decision to donate their eggs. the same study found that 20% of women did not recall being aware of any physical risks. in accordance with the american society for reproductive medicine guidelines, female donors are given a limit of 6 cycles that they may donate in order to minimize the possible health risks. initial evidence suggests that repetitive oocyte donation cycles does not cause accelerated ovarian aging, evidenced by absence of decreased anti-müllerian hormone (amh) in such women. intended parent the recipient has a minimal risk of contracting a transmittable disease. while the donor may test negative for hiv, such testing does not exclude the possibility that the donor has contracted hiv very recently, so the recipient faces a residual risk of exposure. in the us, the fda requires full infectious disease testing no more than 30 days prior to retrieval and/or transfer. many clinics require that donors be retested a few days prior to retrieval so the risk to the recipient is minimal. intimate partners of both the egg donor and the recipient are also tested. the recipient must also trust that the medical history provided by the donor and her family is accurate. as american donors are paid thousands of dollars, such compensation may drive deceptive behaviors from donors. however, a full psychological evaluation is required by most ivf clinics, providing some evaluation of donor trustworthiness. in most cases, there is no ongoing relationship between the donor and recipient following the cycle. both the donor and recipient agree in formal legal documents that the donation of the eggs is final at the time of retrieval, and typically both parties would like any "relationship" to conclude at that point; if they prefer continued contact, they may provide for that in the contract. even if they prefer anonymity, however, it remains theoretically possible that in the future, some children may be able to identify their donor(s) using dna databanks and/or registries (e.g., if the donor submits her dna to a genealogy site and a child born from her donation later submits its dna to the same site). multiple birth is a common complication. incidence of twin births is very high. at the present time, the american society for reproductive medicine recommends that no more than 1 or 2 embryos be transferred in any given cycle. remaining embryos are frozen, whether for future transfers if the first one fails, for siblings, or for eventual embryo donation. there appears to be a slightly higher risk of pregnancy-induced hypertension in pregnancies of egg donation. fetus pregnancies with egg donation are associated with a slightly increased risk of placental pathology. the local and systemic immunologic changes are also more pronounced than in natural pregnancies, so it has been suggested that the association is caused by reduced maternal immune tolerance towards the fetus, as the genetic similarity between the carrier and fetus from an egg donation is less than in a natural pregnancy. in contrast, the incidence of other perinatal complications, such as intrauterine growth restriction, preterm birth and congenital malformations, is comparable to conventional ivf without egg donation. custody generally legal documents are signed renouncing rights and responsibilities of custody on the part of the donor. most ivf doctors will not proceed with administering medication to any donor until these documents are in place and a legal "clearance letter" confirming this understanding is provided to the doctor. legality and financial issues the legal status and cost/compensation models of egg donation vary significantly by country. it may be totally illegal (e.g., italy, germany); legal only if anonymous and gratuitous—that is, without any compensation for the egg donor (e.g., france); legal only if non-anonymous and gratuitous (e.g., canada); legal only if anonymous, but egg donors may be compensated (the compensation is often described as being to offset her inconvenience and expenses) (e.g., spain, czech republic, south africa); legal only if non-anonymous, but egg donors may be compensated (e.g., the uk); or legal whether or not it is anonymous, and egg donors may be compensated (e.g., the us). because most countries prohibit the sale of body parts, egg donors generally are paid for undergoing the necessary medical procedures rather than for their eggs. in other words, if they complete the cycle, they will be paid the agreed price regardless of how many (or how few) eggs are retrieved. in countries that prohibit compensation there is an extreme dearth of young women willing to go through this procedure. additionally, in most countries where it is legal and compensated, the law places a cap on the compensation and that cap tends to be in the vicinity of $1000–$2000. in the us, no law caps the compensation, but the american society for reproductive medicine requires member clinics to abide by their standards, which provide that "sums of $5,000 or more require justification and sums above $10,000 are not appropriate." the "justification" for payments over $5000 may include previous successful donations, unusually good family health history, or membership in minority ethnicities for which it is more difficult to find donors. as a result of these legal and financial differences around the world, egg donation in the us is much more expensive than it is in other countries. for instance, at one top us clinic it costs more than $26,000 plus the donor's medications (another several thousand dollars). having an attorney draft a contract is recommended in order to ensure that the donor has no possible legal rights or responsibilities over the child or any frozen embryos. hiring an attorney who specializes in reproductive law is thus strongly recommended, at least in the united states; other countries may have other procedures for clarifying the parties' rights, or may simply have legislation that defines the parties' rights. in the us, before the egg donor's ivf cycle begins she typically must sign the egg donor contract, which specifies the rights of the donor and the recipient(s) with respect to the retrieved eggs, the embryos, and any children conceived from the donation. such contracts should specify that the recipients are the legal parents of the child and the legal owners of any eggs or embryos resulting from the cycle; in other words, while the donor has the right to cancel the cycle at any time prior to egg donation (although if she does so the contract generally provides that she will not be paid), once the eggs are retrieved they belong to the recipient(s). in individual cases the donors and parents may also wish to negotiate terms relating to any unused embryos (e.g., some donors would prefer that unused embryos be destroyed or donated to science, while others would prefer or allow them to be donated to another infertile couple). some states have also adopted the uniform parentage act, which provides that the recipient or recipients have complete parental responsibility of the conceived child. in buzzanca v. buzzanca, 72 cal. rptr.2d 280 (cal. ct. app. 1998), the court held that both the recipient and the father of a child conceived through anonymous sperm and egg donation and carried by a surrogate were the legal parents of the child by virtue of their procreative intent. therefore, the father was required to pay child support even though he sought a divorce before the child was born. donor registries main article: donor registration a donor registry is a registry to facilitate donor conceived people, sperm donors and egg donors to establish contact with genetic kindred. they are mostly used by donor conceived people to find genetic half-siblings from the same egg- or sperm donor. 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