Figure 1.

Effect of advanced maternal age on oocyte/embryo competence and putative mechanisms impaired by aging. Aging in women causes both a reduction of the ovarian reserve and of the oocyte competence. All the processes impaired may result into a lower energy production/balance involving a small reduction of embryo developmental rate to the blastocyst stage, as well as a higher frequency of chromosome missegregation during maternal meiosis leading to a high increase in blastocyst aneuploidy rate (especially in women older than 35) [data adapted from Franasiak et al. (10) and Capalbo et al. (11)]. Ultimately, these mechanisms converge into a decreased fertility, an increased prevalence of vital chromosomal abnormalities, an increased miscarriage rate, as well as an increased prevalence of numerical chromosomal abnormalities in the newborns [data adapted from Hassold and Hunt (13) and Heffner (4)]. The aneuploidy rate is estimated per biopsied blastocyst; the fertility is estimated as number of babies born per 1,000 married women; the overall prevalence of vital aneuploidies is estimated per clinically recognized pregnancy; the miscarriage rate is estimated per clinical pregnancy; at last, the overall prevalence of numerical chromosomal abnormalities is estimated per number of newborns.