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 account for the decline of fertility with age, the majority of studies agree that poor oocyte quality and reduced endometrial receptivity are the most important. In fact, the increased incidence of early pregnancy loss and chromosomal abnormalities of oocytes in older women, as well as the ability to reverse decreasing pregnancy rates by using oocyte donation, strongly support the evidence that oocyte ageing is the main factor responsible for decreasing fertility. Conversely, the lack of knowledge of the physiological variables that determine a successful nidation 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 donation. Results were reviewed according to the following subclasses of age groups: < or = 30, 31-35 and 36-39 years for donors, and < or = 30, 31-35, 36-40, 41-45 and 46-53 years for recipients.(ABSTRACT TRUNCATED AT 250 WORDS)