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To determine whether undetected aneuploidy contributes to pregnancy loss after transfer of euploid embryos that have undergone array comparative genomic hybridization (aCGH).Case-control study.University-based fertility center.Cases included 38 patients who underwent frozen euploid ET as determined by aCGH, resulting in miscarriage. Controls included 38 patients who underwent frozen euploid ET as determined by aCGH, resulting in a live birth.Next-generation sequencing (NGS) protocols were internally validated. Saved amplified DNA samples from the blastocyst trophectoderm biopsies previously diagnosed as euploid by aCGH were reanalyzed using NGS. Cytogenetic reports of the products of conception for 20 of the pregnancies resulting in miscarriage were available for comparison.The incidence of aneuploidy and mosaicism using NGS within embryos resulting in miscarriage and live birth.Of euploid embryos analyzed by aCGH resulting in miscarriage, 31.6% were mosaic and 5.2% were polyploid by NGS. The rate of chromosomal abnormalities was significantly higher in embryos resulting in miscarriage (36.8%) than in those resulting in live births (15.8%). The rate of mosaicism was twice as high among embryos resulting in miscarriage than those resulting in live birth, but this was not statistically significant. Next-generation sequencing detected more cases of mosaicism than cytogenetic analysis of products of conception.Undetected aneuploidy may increase the risk of first trimester pregnancy loss. Next-generation sequencing may detect mosaicism and triploidy more frequently than aCGH, which could help to identify embryos at high risk of miscarriage. Mosaic embryos, however, should not be discarded as some can result in live births.

Original publication




Journal article


Fertility and sterility

Publication Date





1414 - 1419.e5


New York University Langone Medical Center, New York University Fertility Center, New York, New York. Electronic address:


Blastocyst, Humans, Infertility, Abortion, Spontaneous, Aneuploidy, Preimplantation Diagnosis, Cryopreservation, Treatment Outcome, Embryo Transfer, Fertilization in Vitro, Risk Assessment, Risk Factors, Retrospective Studies, Predictive Value of Tests, Sequence Analysis, DNA, Fertility, Pregnancy, Pregnancy Trimester, First, Mosaicism, Adult, Female, Live Birth, Comparative Genomic Hybridization, Genetic Testing, High-Throughput Nucleotide Sequencing