What is Preimplantation Genetic Testing (PGT)? How does it increase pregnancy chances and reduce miscarriage?
Preimplantation Genetic Testing, or PGT, is a technology used to screen embryos for genetic abnormalities before transferring them into the uterus. It helps reduce the risk of genetic diseases (such as Down syndrome), lowers miscarriage rates, and increases the success rate of IVF/ICSI.
Especially for women over 35 years old, those with a history of pregnancies with genetic abnormalities, couples at risk of passing on abnormal genes or genetic diseases, or those with recurrent miscarriages.
Get to know PGT: Innovation for a perfect baby
In the IVF/ICSI process, selecting embryos that look “good” externally may not be enough because embryos with good appearance may still have hidden chromosomal abnormalities. PGT is like a “gene-level health check” before implantation.
Types of PGT you should know
- PGT-A (Aneuploidy): Checks whether the chromosome count is complete with 23 pairs (prevents Down syndrome)
- PGT-M (Monogenic): Tests for genetic diseases caused by a single gene (e.g., thalassemia, muscular dystrophy)
- PGT-SR (Structural Rearrangement): Detects structural chromosomal abnormalities
Who should undergo embryo chromosome testing?
According to medical recommendations, the following groups will benefit the most:
- Women over 35 years old, as egg quality and chromosome abnormalities increase with age
- Those with a history of consecutive miscarriages, especially in the first trimester (often caused by chromosomal abnormalities)
- Those who have undergone multiple unsuccessful IVF/ICSI attempts, even with good-grade embryos that fail to implant
- Couples who are carriers of genetic diseases, to pass on healthy genes to their children
PGT procedure and safety
This process is performed by expert embryologists.
- Embryo culture: Cultured until the blastocyst stage (day 5-6)
- Cell biopsy: A small number of cells from the part that will develop into the placenta (trophectoderm) are taken without affecting the embryo’s development into a baby
- Result analysis: Uses NGS (Next Generation Sequencing) technology with over 90% accuracy
- Embryo freezing: While waiting for test results (approximately 7-14 days)
Advantages and limitations
| Advantages of PGT | Limitations to be aware of |
|---|---|
| Increases implantation rate | Additional costs beyond regular ICSI |
| Reduces miscarriage rate | There may be no normal embryos to transfer (in cases with poor egg quality) |
| Reduces time to pregnancy | Cannot guarantee 100% healthy babies (only chromosome testing) |
Frequently Asked Questions
-
Does PGT testing risk killing the embryo?
Answer: If performed by an experienced embryologist in a standard laboratory, the chance of embryo damage is very low (less than 1%)
-
Can the baby’s gender be known from chromosome testing?
Answer: According to Thai law, doctors cannot disclose gender for gender selection purposes, except to prevent sex-linked genetic diseases only
PGT is not just about choosing the best embryo but about reducing the pain of miscarriage and increasing the chance for families to welcome a healthy new member.
