Advanced maternal age.

Advanced maternal age is the obvious indication to PGD for aneuploidy. It is very well know indeed how chromosomal abnormalities originating from meiotic errors are the main cause for reduced oocyte quality. More and more data are contributing to an understanding of the reasons for this condition, including the possibility of an age-related diminished energy supply that might affect spindle formation with a consequent increase in meiotic errors. Non-disjunction and random segregation of homologues as well as precocious separation of sister chromatids result in aneuploidy in a way that is strictly dependent on several factors, such as timed loss of chromatid cohesion, cell-cycle control, and granulosa cell functioning. It is not surprising that many years ago, outstanding experts in reproductive biology came to the conclusion that aneuploidy testing on preimplantation embryos could alleviate the age effects by removing from transfer those embryos having an abnormal chromosomal complement. The expectation was to obtain in older patients the same reproductive performance as in younger women. Several studies have supported this hypothesis reporting higher implantation rates concomitantly with lower incidence of spontaneous abortions and trisomic conceptions following embryo selection by FISH analysis. Unfortunately, none of these studies met the proper criteria of a RCT (randomized controlled trial) and their results must be interpreted with caution. Nevertheless, one point is clear, and relates to the need for highly skilled operators and professional training to perform a technique that is very specialized in all its steps. There is no doubt the 'well' biopsied embryos are undisturbed in their implantation potential and this statement represents the starting point for any study aimed at dealing with the clinical application of embryos undergoing PGD. Current knowledge of the meiotic process at oogenesis and the data from clinical pregnancies after PGD for aneuploidy either on embryos or on polar bodies represent the rationale supporting the application of this technique. If the rationale is correct, then there must be a clinical advantage. On the contrary, if no clinical advantage is demonstrated or, even worse, if there is a clinical disadvantage, then we have the duty to understand why and to identify the reasons for this inconsistency and the weak points in our current train of thought. [ABSTRACT FROM AUTHOR]