Increase in the rate of diploidy with maternal age in unfertilized in-vitro fertilization oocytes.

Human oocytes which failed to fertilize in vitro were fixed for cytogenetic analysis. Metaphase II chromosomes were identified in 286 oocytes, of which 233 were suitable for cytogenetic analysis. In all, 181 oocytes had a normal haploid karyotype (77.7%), while the remaining 52 were abnormal (28 aneuploid, 14 diploid and 10 tetraploid). The rate of aneuploidy did not increase with maternal age. However, the proportion of diploid oocytes increased significantly with advancing maternal age (P < 0.01), being particularly obvious in women aged > 35 years.