Pregnancy Rate from the Transfer of a Single Normal Embryo in Women of Advanced Reproductive Age Undergoing PGD for Determi

MII n 5 203 46 (22.7%) 41 (20.2%) 40 (19.7%) 33 (16.3%) 91 (44.9%) GV n 5 93 6 (6.5%)* 3 (3.2%)* 8 (8.6%)† 4 (4.3%)* 18 (19.3%)* *P ,0.05 compared to MII oocytes. †P 50.06 compared to MII oocytes. The data shows that there was a significant difference (P,0.05, Chi Square Test) between the frequency of aneuploidy in MII and GV oocytes for chromosomes 11, 17 and 22 and was bordering on significance for chromosome 16. There was a significant difference (P,0.05, Chi Square Test) in the number of GV oocytes and MII oocytes that were aneuploid for at least one of the four chromosomes. Conclusions: We have shown that aneuploidy occurs in GV oocytes at a frequency of approximately 6% for each of the chromosomes tested, and that almost 20% of GV oocytes have an aneuploidy. The frequency of aneuploidy was significantly greater in MII oocytes confirming that many aneuploidies also occur during the first meiotic division. Importantly, it has also shown that a significant number of oocytes are aneuploid even prior to metaphase I.