Birth of a Healthy Infant after Preimplantation Confirmation of Euploidy by Comparative Genomic Hybridization

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Abstract
During in vitro fertilization, morphologically normal embryos often fail to implant. The implantation rate, defined as the ratio of the number of fetal hearts detected to the number of cleavage-stage embryos transferred, is at best approximately 15 to 20 percent, even in experienced centers.1 Early human embryos have a high frequency of aneuploidy, as determined by fluorescence in situ hybridization. Analysis by this method of three to six chromosomes from every cell in early human embryos generated by in vitro fertilization shows that 50 to 70 percent of these embryos have chromosomal errors, including aneuploidy, polyploidy, and mosaicism.2-4 This rate is higher than the frequency of chromosomal abnormalities found in spontaneously aborted fetuses, indicating that many of the abnormal conceptuses die early in development. In particular, autosomal monosomy, with the rare exception of monosomy 21, has not been observed in fetuses in clinical pregnancies, making it likely that chromosomal abnormalities are responsible for a substantial proportion of implantation failures.