40w LaterGuide

If a genetic condition runs in your family or a previous pregnancy or child was affected by a genetic or chromosomal condition, you may be concerned about the risk in a future pregnancy.

When undergoing IVF, preimplantation genetic testing (PGT) can be used to test embryos for certain genetic or chromosomal abnormalities before embryo transfer.

However, PGT cannot detect every genetic condition, and different types of PGT are used for different purposes.

PGT-M: Testing for specific single-gene conditions

PGT-M is used when there is a known risk of a specific monogenic condition in the family. It tests embryos for the particular genetic variant associated with that condition.

It does not screen embryos for every possible genetic disorder. Genetic counseling and appropriate testing are usually needed before IVF to determine whether PGT-M is possible and appropriate.

PGT-SR: Testing for structural chromosome rearrangements

PGT-SR may be considered when a parent carries a structural chromosome rearrangement, such as a translocation or inversion. It can identify embryos at risk of having an unbalanced amount of chromosome material.

PGT-A: Screening for chromosome-number abnormalities

PGT-A screens embryos for aneuploidy, meaning an abnormal number of chromosomes.

It does not test for all genetic diseases or guarantee that an embryo will result in a healthy baby. Routine PGT-A for every IVF patient has not been shown to improve overall reproductive outcomes for everyone.

How is PGT performed?

PGT generally requires IVF. After fertilization, embryos are cultured in the laboratory. At the blastocyst stage, several cells are usually biopsied from the trophectoderm and sent for genetic testing.

Does a normal PGT result guarantee a genetically healthy baby?

No. PGT examines specific genetic or chromosomal findings and cannot detect every possible condition. False-positive or false-negative results can also occur.

What does a mosaic result mean?

Sometimes the tested cells show a mixture of cells with different chromosome findings. This is called a mosaic result. Because PGT tests only a small sample of cells from an embryo, interpretation can be complex and genetic counseling may be helpful.

Do I still need prenatal testing after PGT?

PGT does not replace prenatal genetic screening or diagnostic testing. After pregnancy is established, prenatal screening and diagnostic options such as chorionic villus sampling (CVS) or amniocentesis should still be discussed.

PGT is therefore best understood as a way to obtain information about specific genetic or chromosomal risks before embryo transfer, rather than a test that guarantees a baby without genetic conditions.