There are two types of preimplantation genetic testing as follows: 

1. PGT-A (Preimplantation Genetic Testing for Aneuploidy)
A person typically has 46 total chromosomes or 23 pairs of chromosomes, with 22 pairs of body chromosomes and one pair of sex chromosomes. An extra copy or a missing copy of chromosome can cause physical and intellectual disabilities. PGT-A (Preimplantation Genetic Testing for Aneuploidy) screens all 23 pairs of chromosomes for abnormalities. With the Next Generation Sequencing (NGS) technology, PGT-A is currently a modern standardized test offering a highly detailed analysis of chromosomes with high accuracy.

2. Preimplantation Genetic Testing for Monogenic Disorder (PGT-M)
PGT-M involves testing embryos created through in vitro fertilization (IVF) for monogenic/single gene defects inherited from the father or the mother prior to transfer of unaffected embryos to the uterus. Without the screening, either parent or both parents with genetic defects may pass the defects on to the fetus. There are many single-gene diseases. The common ones include thalassemia, anemia, cystic kidney disease, and BRCA1 or BRCA2 genetic mutations, which cause certain cancers like breast and ovarian cancers. 
 

This testing follows the ICSI, (intracytoplasmic sperm injection). When the embryo reaches the blastocyst stage (5-6 days after fertilization), with inner cell mass (ICM) that will develop into an embryo proper and more than 100 trophectoderm (TE) cells that will develop into the placenta, just a few cells in the trophectoderm component are removed for the analysis. The biopsy has no impact on the embryo development nor the cells developing into a fetus.
 

• Increased pregnancy success rate to 70-80% for embryos tested for chromosomal abnormalities
• Reduced risk of miscarriages
• Increased chance of healthy pregnancy

• Women over 35 years old
• Women with a history of recurrent IVF failures
• Women with a history of hereditary diseases such as anemia, thalassemia, cystic kidney disease, and certain types of cancer like breast cancer
• Couples with a family history of genetic diseases or whose first-born has chromosomal abnormalities
• Women with a history of more than two  miscarriages due to an abnormality in the baby's chromosomes or unknown cause