One of the most tragic experiences for couples trying to conceive is a positive pregnancy test, followed by a miscarriage. Pregnancy loss is devastating no matter when it happens, but it’s especially crushing for those dealing with infertility. And for those couples or individuals who opt for IVF as a path to parenthood a failed embryo transfer is every bit as heartbreaking.
Miscarriage and failed embryo transfer commonly occur due to abnormal embryo genetics. However, some embryos survive the pregnancy and may be born with a variety of birth defects from a cleft palate to severe heart or neural tube defects such as spina bifida. In some cases the baby is stillborn.
PGT with IVF or Fertility Preservation
For couples going through IVF there is an option for PGT or preimplantation genetic testing. This beneficial process tests cells from in vitro embryos, prior to implantation, for a variety of genetic and chromosomal abnormalities which may cause birth defects, failed embryo transfer, miscarriage or stillbirth. Based on recent studies PGT results in 50% greater pregnancy rates per transferred embryo.
PGT is also useful when freezing eggs for fertility preservation. Upon fertilization the egg removes half of its chromosome to accommodate the chromosome from the sperm. It’s possible to remove the forfeited chromosomes, also known as the “polar body”, prior to cryopreservation. At this time the lab checks for chromosomal abnormalities which provide genetic information about the egg.
What Abnormalities Does PGT Uncover?
Preimplantation genetic testing checks for a number of chromosomal and genetic abnormalities in the embryo that could result in birth defects, miscarriage or failed embryo transfer. Your physician chooses embryos free from any abnormalities for implantation. This increases your odds of a successful pregnancy and delivery. There are four categories of PGT that test for specific genetic and chromosomal disorders. They are:
PGT-A: The A stands for Aneuploidy, the greatest cause of miscarriage, failed implantation and birth defects. This method analyzes cells from the embryo for the number of chromosomes. A normal embryo has 46 chromosomes, 23 from each biological parent. An unequal division of sperm or egg cells results in too few or too many chromosomes. Monosomy is the absence of a chromosome and trisomy is an extra chromosome. Turner syndrome, the absence of an X chromosome is an example of monosomy. It affects female embryos only and causes a variety of developmental and medical issues. Down syndrome is an example of trisomy and affects one in 700 babies in the US.
PGT-M: Monogenic, meaning single cell abnormalities, identify the existence of a single-cell disease such as:
- Sickle Cell
- Huntington’s disease
- Muscular Dystrophy
- Fragile X
- Cystic Fibrosis
- Tay-Sachs
- Polycystic Kidney disease
PGT-SR: This tests for structural rearrangement of the chromosomes. Structural rearrangement, such as translocation or inversion, occurs when one of the parents carries a chromosomal inversion. When the parent has a structural rearrangement, they are at greater risk for producing embryos with chromosomal disorders. A live birth using these embryos is highly unlikely. SR is a common cause of recurring miscarriage.
PGT-HLA: Human Leukocyte Antigen is a marker found on most of the cells in your body. HLA alerts your immune system when there is a cell that doesn’t belong in your body. Using this test on your embryos, for example, helps identify whether or not the embryo is a match for a sibling with leukemia. If so, the cord blood is useful for a possible transplant.
Who Should Consider PGT?
PGT is available for anyone going through IVF or cryopreservation of their eggs. Those who are most at risk for genetic abnormalities and chromosomal issues are absolutely candidates for PGT. In fact you should inquire about PGT if you are:
- A woman over the age of 37 due to the higher risk of abnormal embryo genetics related to age.
- Couples who’ve experienced recurrent miscarriages.
- Couples at risk for having a child with a genetic or inherited disease.
Are There Risks to PGT?
No known risks to babies born after PGT exist and the test became the norm for high risk patients roughly 20 years ago. Because PGT can’t test for all possible birth defects patients should take advantage of prenatal testing, such as amniocentesis and chorionic villi sampling, while pregnant.
Reach Out for More Information
At LA IVF we partner with you on your fertility journey. We sincerely want to see your dream of parenthood come true and strive to help make it happen. For information on PGT or any other aspect of fertility treatment, please contact our office.