OOCYTE DONATION IN HUMANS - A MODEL TO STUDY THE EFFECT OF AGE ON EMBRYO IMPLANTATION RATE

Although a number of different mechanisms have been suggested to accou nt for the decline of fertility with age, the majority of studies agre e that poor oocyte quality and reduced endometrial receptivity are the most important. In fact, the increased incidence of early pregnancy l oss and chromosomal abnormalities of oocytes in older women, as well a s the ability to reverse decreasing pregnancy rates by using oocyte do nation, strongly support the evidence that oocyte ageing is the main f actor responsible for decreasing fertility. Conversely, the lack of kn owledge of the physiological variables that determine a successful nid ation of a human embryo makes the analysis of uterine receptivity much more difficult. In order to evaluate the impact of the age of donors and recipients on pregnancy, implantation and abortion rates, we have retrospectively analysed 258 cycles from our programme of oocyte donat ion. Results were reviewed according to the following subclasses of ag e groups: less than or equal to 30, 31-35 and 36-39 years for donors, and less than or equal to 30, 31-35, 36-40, 41-45 and 46-53 years for recipients. For each group of recipients, the average age of the donor s, the length of cycle of hormone replacement therapy and the ultrason ographic images of the endometrium were almost identical. Implantation rates achieved with donated oocytes appeared to be negatively associa ted with the donor age (18.4, 15.5 and 11.4% respectively). The data s howed statistical significance by the chi(2) test specifically for don ors' age greater than or equal to 36 years. This was not confirmed, ho wever, by logistic regression analysis. Results reported according to the different recipients' age groups were similar for implantation (13 , 21 17, 14, and 12% respectively) and abortion (17, 13, 11, 14 and 7% respectively). We conclude that the age of women producing oocytes ma y affect the chances of embryo implantation, while the women receiving donated oocytes, at least in the range of 30-50 years of age, have eq ual chances of successful embryo implantation and nidation maintenance .