Healthy live births from transfer of low-mosaicism embryos after preimplantation genetic testing for aneuploidy.

Purpose: This study evaluated the potential viability of embryos with low mosaicism level (< 50%) by comparing the clinical outcomes of single mosaic versus euploid blastocyst transfer. In addition, the live birth outcomes for various types of mosaicism with respect to abnormalities in chromosome structure and content were analyzed.
Methods: This study included patients who underwent in vitro fertilization with preimplantation genetic testing for aneuploidy (PGT-A). The PGT-A cycles performed through next-generation sequencing with single euploid or mosaic embryo transfers were included. We collected 299 frozen single embryo transfer cycles-216 single euploid and 83 mosaic-between July 2016 and July 2018. This study analyzed clinical outcomes, including fetal karyotyping by using amniocentesis, gestational age at delivery, and live birth weight after single mosaic embryo transfer.
Results: The average birth weight of infants in the euploid and mosaic blastocyst transfer groups was 3146.2 and 2997.7 g, respectively. The karyotyping results of prenatal diagnosis in all pregnant women were normal. Our study indicated that mosaic embryos can develop into euploid healthy infants with various levels or types of mosaicism. No significant difference was observed between infants from euploid and mosaic blastocyst transfers.
Conclusion: If patients have no euploid embryos, mosaic embryos can be transferred as they have potential for implantation and development into euploid healthy infants. This study is invaluable for counseling clinical results after single mosaic embryo transfers.