Poor oocyte quality rather than implantation failure as a cause of age-related decline in female fertility.

Female fertility declines with advancing age. To establish whether this age-related reproductive failure results from diminished oocyte quality or uterine/endometrial inadequacy we investigated ovum donation in 35 infertile women, aged 40 years or older (mean 42.7 [SE 0.3]) who had failed at attempts at conception with their own (self) oocytes. Oocytes were donated by 29 young individuals (mean age 33.4 [0.7]) undergoing in-vitro fertilisation (IVF). 8 (5.3%) pregnancies were achieved in 150 cycles of ovulation induction with self-oocytes and 2 (3.3%) in 60 such cycles by in-vitro fertilisation (IVF), but none attained viability. By contrast in 50 cycles with donated oocytes 28 (56%) pregnancies and 15 (30%) deliveries were realised (p less than 0.005). The rate of implantation per embryo transferred was higher (14.7%) with donated oocytes than that with self-oocytes (3.3%) (p less than 0.01). To further elucidate the contribution of age to reproductive outcome, pregnancy results were compared between the young donors and older recipients. Both donors and recipients shared oocytes from the same induced cohort. Rates for clinical pregnancy and delivery did not differ between donors (33% and 23%) and recipients (40% and 30%). Our data suggest that the age-related decline in female fertility is attributable to oocyte quality and is correctable by ovum donation. The uterus can adequately sustain pregnancies even when reproductive potential is artificially prolonged into the late 40s.