Mosaicism means that some cells within an embryo have a normal number of chromosomes, and some have an abnormal number. With PGT-A testing, a biopsy of one or more cells is tested to screen embryos for chromosomal abnormalities. If there is mosaicism within an embryo, it is possible that the cell(s) of an embryo biopsy sample would not be representative of the remaining cells in the embryo. Some forms of PGT-A have the potential to find mosaicism within an embryo biopsy sample, but no form of PGT-A can detect mosaicism between the cells of the biopsy and the cells of the remaining embryo. Mosaicism is not reported on Spectrum SNP array reports, but if present in a biopsy sample, it could potentially result in decreased confidence calls on the result report. If reporting on mosaicism is important for you, your provider may consider the Spectrum NGS test instead.