Age, pregnancy and miscarriage: uterine versus ovarian factors.

This study was performed to evaluate the relative contribution of oocyte and uterine factors to the age-related reduction in fecundity. The pregnancy and miscarriage rates in women receiving donated oocytes were compared to those in women using their own oocytes in in-vitro fertilization (IVF) and gamete intra-Fallopian transfer (GIFT) procedures. Oocyte donation with embryo transfer was performed on 241 women in 371 cycles; 116 of these women became pregnant (48% per patient and 31.5% per cycle) of whom 40 (35%) miscarried, giving a live birth rate of 20.5%. Assisted conception, in the form of IVF/GIFT procedures, was performed on 1331 women using their own oocytes in 2194 cycles; 627 of these women became pregnant (47% per patient and 28.7% per cycle), of whom 228 (36%) miscarried, giving a live birth rate of 18.2%. Neither the age of the donor nor the age of the recipient was related to pregnancy rate. The age of the donor, however, was directly related to the miscarriage rate. On the other hand, the age of patients undergoing IVF/GIFT was inversely related to the pregnancy rate and directly related to the miscarriage rate. In women of 40 years or over, the overall pregnancy and live birth rates were significantly higher and the miscarriage rate was significantly lower in the group receiving donated oocytes compared to the group using their own oocytes. In summary, we suggest that the age-related decline in fecundity is associated with the age of the oocytes rather than the age of the uterus.