Preimplantation genetic testing for aneuploidy (PGT-A) is significant for assessment of chromosomal aneuploidy for improving clinical outcome of invitro fertilization. Techniques such as comprehensive chromosome screening (CCS) were developed that indicates that aneuploidies may occur in any of the 24 chromosomes in preimplantation embryos. Preimplantation genetic screening (PGS) can be performed using the fluorescence in situ hybridization (FISH) technique for chromosomal aneuploides. Advancement in next-generation sequencing (NGS) technology and microarray technique enhance examination of chromosomal aneuploidies. Different conditions such as subchromosomal abnormalities, segmental aneuploidies, or embryonic mosaicism leads to failure in producing a live birth. A problem that frequently arises when examining heterozygous loci in single cells is allele drop-out (ADO). Elimination of polyzygotic multiple gestation improves obstetrical and neonatal outcomes for many infertile couples. Improved PGT-A techniques leads to more accurate selection of embryos with normal chromosomes.