Embryo morphology, developmental rates, and maternal age are correlated with chromosome abnormalities

To determine some of the unresolved questions related to chromosome anomalies in early human embryos, such are the detection of any advanced maternal age effect; the complete assessment of mosaicism, which requires analysis of all cells; and the relationship with embryonic dysmorphism. Fluorescence in situ hybridization has been used in this study to answer these issues.

Fluorescence in situ hybridization analysis of human embryos using simultaneously probes for three or five chromosomes. Five hundred twenty-four cleavage-stage human embryos obtained by IVF were analyzed by fluorescence in situ hybridization. Embryos were allocated into three groups according to morphological and developmental characteristics (arrested; slow and/or fragmented; morphologically and developmentally normal). The embryos also were analyzed according to maternal age.

Dysmorphic embryos had higher rates of polyploidy and diploid mosaicism. Aneuploidy increased with maternal age in nonarrested embryos. Preimplantation genetic diagnosis successfully detected these abnormalities.

This study demonstrates that, in morphologically and developmentally normal human embryos, cleavage-stage aneuploidy significantly increases with maternal age. The results suggest that implantation failure in older women largely could be due to aneuploidy.