PGS involves testing an embryo for chromosomal abnormalities. Many embryos with chromosomal abnormalities will not lead to a pregnancy, or will result in a miscarriage.

All women will have some eggs that are chromosomally abnormal.

All men will have some sperm that are chromosomally abnormal.

The percentage of embryos that are abnormal can be affected by many factors, including the age and health history of the parents.

PGD involves testing an embryo for rare genetic disorders. This is done before implanting the embryos into the uterus.

PGD is done so that embryos unaffected by the disorder can be transferred to the uterus and those affected can be discarded.

Genetically healthy embryos are transferred to the uterus, where they may attach to its lining and produce a pregnancy.

However, this requires specific probe formation for your disorder and blood work up prior to PGD testing.

It is different from PGD in that probes are already prepared for your particular disorder, as it is a known disorder. Your embryos can be tested for abnormal chromosomes before they are transferred to the uterus. This is called preimplantation genetic testing, or PGT.

Cells from the embryo can be tested for a gene that may produce a specific disease. This will show if an embryo is normal (no disease) or affected (has the disease). It will also show if the embryo is carrying the disease but unaffected by it.

An unaffected carrier is someone who can pass the disease to his or her children, but does not personally have any signs of the disease.

Egg removal followed by ICSI followed by embryo biopsy taken on Day 3 or Day 5 of the embryo and sent for and sent for genetic testing while the embryo is growing in the IVF laboratory.

The testing can be done at different stages using different techniques.

Techniques include fluorescent in situ hybridization (FISH),

Microarray Comparative genomic hybridisation (CGH), and

Single-nucleotide polymorphism (SNP).

Techniques are constantly evolving and changing to be more accurate, easier to run, and give more information. Newer techniques that include microarray and genome sequencing are more common methods of genetic testing.

PGD is for someone who has or is a carrier of a genetic disorder.

PGS may be recommended for someone with recurrent miscarriage, someone who is older or whose ovaries do not work as well as expected, or someone with multiple failed fertility treatments. Some couples also can choose to do PGS for personal reasons.

Anyone interested in PGD or PGS should consult with a fertility specialist so that the procedure and any alternatives can be discussed.