Defective Oocytes are not a Common Cause of Unexplained Inferitlity as Determined by Evaluation of Sharing Oocytes Between Infertile Donors and Recipients

Abstract

BACKGROUND: When no cause of infertility can be found in a couple or an infertility defect is diagnosed but correction does not lead to successful pregnancy after a reasonable number of treatment cycles the couple is considered to have unexplained infertility. Theoretically the cause of the unexplained infertility factor could be defective oocytes, defective sperm, an endometrial factor, or an occult tubal factor. OBJECTIVE(S): To determine the role of defective oocytes as an etiological factor in unexplained infertility by comparing pregnancy outcome in infertile oocyte donors and their respective recipients according to the etiology for the donor's infertility problem. MATERIALS AND METHOD(S): A retrospective comparison was made of fertilization and pregnancy rates in infertile women undergoing in vitro fertilization-embryo transfer (IVF-ET), sharing oocytes with a recipient in need of donated oocytes. The pregnancy outcome in the oocyte donors with unexplained infertility would be compared to the outcome of their respective recipients and to donors and recipients where the cause of infertility in the donors was either a tubal or male factor. Data were further stratified according to use of ICSI or not. RESULT(S): For infertile oocyte donors the clinical pregnancy rate per transfer was 60% (6/10) for couples with unexplained infertility vs. 52.5% (32/61) for couples with male factor vs. 48.6% (67/138) for couples with tubal factor. The respective live delivery rates were 60%, 45.9%, and 42.8%, respectively. The implantation rates for these 3 groups were 41.7% (10/24) vs. 30.3% (50/165) vs. 27.9% (105/377). For their respective recipients, the clinical pregnancy rate per transfer was 60% (9/15) for recipients using donors with unexplained infertility vs. 51.3% (40/78) for male factor vs. 60.1% (86/143) for tubal factor. The respective live delivery rates were 53.3%, 37.2%, and 53.1%, respectively. The implantation rates were 33.3% (14/42) vs. 27.0% (62/230) vs. 34.2% (151/441) (p=NS, chi-square). There was a generalized trend for higher pregnancy rates per transfer using conventional oocyte insemination vs. ICSI. There was a 12.5% failed fertilization rate in the unexplained infertility group using conventional insemination. CONCLUSION(S): It does not appear that a defective oocyte, resulting in an embryo of poor implantation potential, is a common cause of unexplained infertility. This conclusion is evidenced by not only failing to show a difference with donors with unexplained infertility with their respective recipients but not with other donors or recipients receiving oocytes from donors with tubal factor or male factor. SUPPORT: None