How Genetic Testing Improves IVF
In vitro fertilization (IVF) is just one of many types of assisted reproductive technologies (ART), but is probably the most well-known option. For couples struggling to conceive naturally, the process offers a very high success rate and can be adapted to improve conception outcomes. Sometimes, underlying issues like having a genetic predisposition to a medical condition could be impacting an individual’s chances of conceiving. When this scenario is a possibility, fertility specialists might recommend undergoing genetic testing.
Defining genetic testing
Genetic testing is a screening performed to determine whether an individual has any known conditions that could affect the odds of conception or be passed down to future offspring. In reality, screening can be performed on individuals or couples regardless of whether pregnancy occurs naturally or via ART. If performed before getting pregnant or earlier in gestation, a simple blood test is usually sufficient to screen for genetic abnormalities. Within the IVF timeline, genetic testing can be performed at a variety of intervals. Most commonly, potential parents are both tested before beginning a cycle, and any embryos developed during the process can also be tested before the embryo transfer step.
Testing parents and donors
IVF is designed to optimize outcomes, so pre-cycle testing is one of the most common screens that is performed. Specialists will screen all participants, including anonymous egg or sperm donors, surrogates, and even the individuals or couples seeking out fertility assistance. Note that women freezing eggs can also request genetic testing to determine viability and if health concerns are present. Testing before conception is referred to as genetic carrier screening and is designed to check for underlying genetic conditions that either make conception harder or increase the chances of passing down an inherited disability. While optional for first-time participants, people with a history of previous failed IVF attempts will be strongly encouraged to get tested.
The PGT Difference
Within IVF, the most common screenings performed are classified as preimplantation genetic testing (PGT). PGT can be further divided into preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS). Both tests are timed after fertilization but before the embryo transfer stage.
PDG versus PGS
Both tests occur before the embryo transfer stage, but are used for very different concerns. PGD is a good option for participants who are known carriers of a genetic disorder and who request that embryos be tested for that condition. Alternatively, PGS is more similar to prenatal genetic testing that pregnant women undergo in the first trimester. The test specifically looks for chromosomal abnormalities that are more likely to lead to failed implantation or miscarriage.
How PGT is performed
Within the IVF timeline, PGT screening is usually performed during assisted hatching, which involves cracking the egg’s shell to facilitate the sperm’s ability to penetrate the egg. If an embryo is formed and later becomes a blastocyst, the technician biopsies cells for genetic screening. The healthiest embryos are transferred to a woman’s uterus.
Who is an ideal candidate?
Not every individual or couple undergoing IVF is automatically an ideal candidate for PGT or even genetic carrier screening before beginning a round. However, if known infertility is present, genetic carrier screening may be recommended before beginning IVF. With PGT, people aged 37 and older or with a history of multiple miscarriages who are attempting IVF are the ideal candidates. Likewise, having a family history of genetic diseases would trigger a PGD screening recommendation.
