Efficacy of oocytes donated by older women in an oocyte donation programme

Population and insemination studies indicate that women experience declining fertility with ageing. The question therefore arises whether older women are suitable oocyte donors. This study addresses this issue by examining the relationship between oocyte donor age and clinical outcome in a large oocyte donation programme. We retrospectively reviewed data from 458 consecutive oocyte donation cycles completed by 164 different designated oocyte donors. Data were divided into two groups: group A, cycles with donors aged 21-30 years at the time of follicular aspiration (193 cycles, 88 donors); and group B, cycles with donors aged 31-40 years at the time of follicular aspiration (265 cycles, 86 donors). Five donors, because of ageing during repetitive donations, contributed data to groups A and B. In a given cycle, all oocytes for a recipient came from only one designated donor. Comparing the two donor groups, there was no difference in the amount of gonadotrophin used to achieve optimal stimulation; however, more oocytes were obtained from group A than group B donors (16.8 +/- 6.9 and 15.1 +/- 8.1 respectively, P < 0.05). Similar percentages of oocytes were fertilized in each group, resulting in the transfer of comparable numbers of embryos (4.5 +/- 1.1 and 4.4 +/- 1.3 respectively). Comparable clinical pregnancy rates were achieved (group A, 36%; group B, 37%). The spontaneous abortion rates were also similar (group A, 20%; group B, 12%), resulting in comparable ongoing and delivered pregnancy rates per cycle (group A, 29%; group B, 32%) and per embryo transferred (group A, 6.4%; group B, 7.3%). In conclusion, women of proven fertility should not be excluded from donating oocytes simply because of their age. There exists a cohort of fertile women who resist the decreasing fecundity and increasing spontaneous abortion rates associated with ageing. With careful screening, many women of proven fertility can donate oocytes until the age of 40 years with an efficacy equal to that of younger women. Given the relative shortage of suitable oocyte donors, and increasing requests from recipients with previous donor oocyte babies to obtain oocytes from the same, now older, donor, the findings of this study are of practical clinical importance.