Humans are incredibly inefficient when it comes to reproduction.
FISH, however, can be reliably used for only a few chromosomes at a time. Eight embryos were mosaic, containing different chromosome complements in different cells. The presence of three completely normal embryos was actually surprising given the high frequency of abnormalities detected with just a few FISH chromosome probes, but can be explained by the clustering of multiple aneuploidies in single cells. All the aneuploidy may arise from the lack of a mitotic checkpoint in early embryonic cells. To get around this deficiency, and improve the success rate of IVF, a simplified version of the current protocol could be used to analyze a single cell extracted from early embryos.