Oocyte Donation | Assisted Reproduction
Oocyte (egg) donation is an integral part of modern assisted reproductive care and is associated with the highest success rates. Originally offered to women with primary ovarian insufficiency (premature ovarian failure) or those who had genetic diseases who did not want to transmit the gene defect to their offspring, donated oocytes are now used by women with many reproductive disorders and commonly by women in later reproductive years, Oocyte donation is, at present, the only effective therapy for the treatment of infertility in women with ovarian failure and for the vast majority of women of advanced reproductive age.
Oocyte donation has been proven to be a successful option for women who cannot conceive with their oocytes because of advanced age, diminished ovarian reserve, or genetic disease. Oocyte donation allows the female partner to carry and deliver a pregnancy with her husband’s genetic contribution.
The success of oocyte donation is mainly limited by the age of the donor, who should optimally be younger than 35 years old. Although endometrial receptivity may diminish somewhat with age, the contribution of this uterine factor appears minimal in comparison to oocyte quality. For this reason, the optimal number of embryos to be transferred to the recipient is also principally determined by the donor’s age, rather than that of the recipient age.
Oocyte donors may be either known or unknown to the recipient. Known donors are often biologically related donors (e.g., sister or cousin donors). Because most donors and particularly anonymous donors are young, their oocytes and resultant embryos offer excellent pregnancy rates. The risks of the ART procedure for the donor are confined to the risks associated with stimulation and retrieval because the donor does not carry the pregnancy. The primary risk of donation for the recipient is the transmission of infection. Despite the fact that the donors are screened at multiple intervals for infectious disease, the fact that fresh embryos are used, because of lower implantation rates with frozen embryos, poses a small theoretical risk of transmission of diseases such as human immunodeficiency virus (HIV), although such transmission has not been documented with oocyte donation. Although this risk appears to be mainly theoretical, the alternative of cryopreserving and quarantining embryos resulting from donor oocytes should be discussed with recipients as an option.
A key component of successful oocyte donation is the synchronization of the recipient’s menstrual cycle with the donor’s cycle. In a recipient with intact ovarian function, this can be achieved through GnRH agonist downregulation followed by hormonal support with exogenous estrogen and progesterone. A mock cycle is undertaken before actual donor oocytes IVF to ensure that the recipient responds appropriately to hormonal support and that her endometrial lining develops adequately. In the event of pregnancy via donor oocytes IVF, estrogen and progesterone support are continued throughout the first trimester.