PGD, or preimplantation genetic diagnosis, is a test performed on embryos during IVF to check for specific inherited genetic conditions before pregnancy begins. The term PGD was officially replaced in 2017 with a newer name, PGT-M (preimplantation genetic testing for monogenic disorders), but many people and clinics still use “PGD” in everyday conversation. The goal is straightforward: identify which embryos carry a known genetic mutation so only unaffected embryos are transferred to the uterus.
How PGD Differs From Other Embryo Testing
PGD (now PGT-M) is not the same thing as PGS, the other common abbreviation you’ll see in fertility discussions. PGS was renamed PGT-A, and it screens embryos for missing or extra chromosomes, conditions like Down syndrome. PGT-A is a broader screening tool. PGD/PGT-M, by contrast, looks for a single specific gene mutation that one or both parents are known to carry. Think of it this way: PGT-A asks “does this embryo have the right number of chromosomes?” while PGD asks “does this embryo carry the family’s cystic fibrosis mutation?”
There’s also a third type called PGT-SR, which tests for structural chromosome rearrangements like translocations or inversions. All three fall under the umbrella of preimplantation genetic testing, but they answer different questions and use somewhat different analytical methods.
What Conditions PGD Can Detect
PGD was originally developed for Mendelian disorders, conditions caused by a mutation in a single gene. Over 200 single-gene disorders have been identified through PGD. The most commonly tested conditions include cystic fibrosis, sickle cell disease, beta-thalassemia, Huntington’s disease, Fragile X syndrome, spinal muscular atrophy, and myotonic dystrophy.
It also covers mutations that raise cancer risk, such as BRCA1 and BRCA2 gene variants linked to breast and ovarian cancer. This is an important distinction: PGD isn’t limited to diseases that appear in childhood. It can test for late-onset conditions like Huntington’s, where symptoms may not emerge until midlife, and for mutations that significantly increase lifetime risk of certain cancers rather than guaranteeing disease.
Chromosomal disorders and mitochondrial conditions can also be tested through preimplantation genetic testing more broadly, though mitochondrial testing is still a developing area.
How the Testing Process Works
PGD requires IVF. There is no way to test an embryo’s genes without creating embryos in a lab first. The process begins with ovarian stimulation, where daily hormone injections encourage the ovaries to produce multiple eggs instead of the usual one. Monitoring through ultrasound and blood work continues for roughly 10 to 14 days until the follicles reach the right size. A trigger shot completes egg maturation, and egg retrieval happens 34 to 36 hours later under sedation.
Retrieved eggs are fertilized in the lab, typically using a technique called ICSI where a single sperm is injected directly into each egg. Fertilization is checked 16 to 18 hours later. The resulting embryos are then cultured for five to seven days until they reach the blastocyst stage, a hollow ball of roughly 100 to 200 cells.
At this point, an embryologist removes a small cluster of cells from the outer layer of the blastocyst (the part that will become the placenta, not the baby). These cells are sent to a genetics laboratory for analysis while the embryos are frozen. Results typically come back within one to two weeks. If unaffected embryos are identified, one is thawed and transferred in a subsequent cycle, called a frozen embryo transfer.
PGD Requires Advance Preparation
Unlike PGT-A, which uses a standard screening panel, PGD for a single-gene disorder requires custom test development before your IVF cycle even begins. The genetics lab needs to build a probe specific to your family’s mutation. This setup process, sometimes called test development or workup, involves collecting DNA samples from the carrier parent(s) and often from close relatives to map the mutation within the family’s genetic background. It can take several weeks to several months, so planning ahead matters.
This customization is one reason PGD costs more than standard chromosome screening and why your fertility team will typically recommend genetic counseling early in the process.
How Accurate Is PGD?
When the specific mutation is known and the embryo has a clear genetic result, accuracy exceeds 95%. A 2025 meta-analysis published in Reproductive Biology and Endocrinology found that the diagnostic accuracy of testing for structural rearrangements reached an area-under-the-curve (a measure of overall test performance) of 0.957, which is considered excellent. Testing for chromosome number was somewhat lower at 0.806.
The main source of diagnostic uncertainty is mosaicism, a situation where different cells within the same embryo have different genetic makeups. When mosaic embryos were excluded from analysis, overall diagnostic accuracy jumped from 0.878 to 0.926, with sensitivity and specificity both reaching about 87%. In practical terms, this means the test is highly reliable but not perfect. A small percentage of results may be inconclusive or, rarely, inaccurate. Prenatal testing during pregnancy is still recommended as confirmation.
Who Should Consider PGD
PGD is indicated when one or both partners carry a known genetic mutation for a serious condition, or when there is a documented family history of a single-gene disorder. Common scenarios include couples where both partners are carriers of a recessive condition like cystic fibrosis (each pregnancy would carry a 25% chance of an affected child), one partner carries a dominant condition like Huntington’s disease (50% chance of passing it on), or one partner carries an X-linked condition like Fragile X.
The American Society for Reproductive Medicine’s 2024 guidance notes that routine genetic testing of all IVF embryos (PGT-A, the chromosome screening version) has not been shown to benefit every patient population. For example, ASRM found insufficient evidence to recommend it routinely for recurrent pregnancy loss, advanced paternal age, or donor egg cycles. PGT-A may help patients of advanced maternal age who still have good ovarian reserve, but this is a separate question from PGD for a known mutation. When a specific heritable condition is at stake, the case for PGD is much more clear-cut.
What PGD Costs
PGD is expensive, and it comes on top of an already costly IVF cycle. In the U.S., PGT-M (the single-gene version) typically runs $7,000 to $12,000 per IVF cycle. This includes the custom test development, the embryo biopsy performed by the clinic’s embryology team, and the genetic laboratory analysis. The cost varies by clinic, lab, and the number of embryos tested, since many labs charge per embryo or in tiers.
For comparison, the simpler PGT-A chromosome screening adds about $4,000 to $5,000 per cycle. Both types of testing also require a frozen embryo transfer rather than a fresh transfer, which adds another $2,000 to $5,000 depending on the clinic. All told, an IVF cycle with PGD can easily exceed $30,000 when you factor in the base IVF costs, medications, testing, and the transfer.
Insurance coverage varies widely. Some states mandate fertility treatment coverage, and some insurance plans cover genetic testing when a documented medical indication exists. But many patients pay out of pocket for some or all of these costs. It’s worth requesting a detailed cost breakdown from both your clinic and the genetics lab before starting, since the billing typically comes as two separate charges.
Limitations Worth Understanding
PGD can only test for conditions the lab has been set up to detect. If you carry a mutation that hasn’t been identified through prior genetic testing, PGD won’t catch it. The process also requires enough embryos to make testing worthwhile. If ovarian stimulation produces only one or two embryos, there’s a real possibility that none will be unaffected, leaving no embryos to transfer in that cycle.
The biopsy itself removes cells from the outer layer of the embryo, which is representative but not identical to the inner cell mass that becomes the fetus. This is why mosaicism can occasionally lead to discordant results. The test also cannot guarantee a live birth. It identifies genetic status, but embryo implantation and healthy pregnancy depend on many additional factors.
For couples with a serious heritable condition, PGD offers something no other reproductive option provides: the ability to start a pregnancy knowing the embryo does not carry the family’s specific mutation. That clarity, while it comes at significant financial and emotional cost, is the core value of the test.