Lots of doctors are very excited about PGD (Preimplantation Genetic Diagnosis), and many IVF patients are equally enthusiastic about it. The idea sounds extremely attractive and logical. If we can take a small biopsy from an embryo and check whether it is genetically normal before transferring it into the uterus, surely that should improve pregnancy rates. After all, transferring a “normal” embryo should increase the chances of success.
At first glance, this seems like a very sensible strategy. Unfortunately, the reality is more complicated than the marketing suggests.
The Problem With the Term “PGD”
One of the biggest sources of confusion is the term itself.
The phrase Preimplantation Genetic Diagnosis sounds very powerful. It suggests that doctors can perform a comprehensive genetic analysis of the embryo before it is implanted. Patients understandably assume that this means the embryo has been thoroughly tested and declared genetically normal.
But in the vast majority of IVF cases, this is not what is actually happening.
In reality, what most clinics are doing today is not truly genetic diagnosis. Instead, they are performing what is more accurately called chromosomal screening for aneuploidy. This is often referred to as PGS (Preimplantation Genetic Screening) or PGT-A (Preimplantation Genetic Testing for Aneuploidy).
What this testing really does is count the number of chromosomes in the embryo.
Humans normally have 46 chromosomes. If an embryo has extra chromosomes or missing chromosomes, it is called aneuploid. These abnormal embryos are less likely to implant and are more likely to result in miscarriage.
So the test is essentially checking whether the embryo has the correct number of chromosomes. That’s useful information, but it is not the same thing as diagnosing genetic health.
Why This Distinction Matters
Because the test is only looking at chromosome numbers, it cannot detect the vast majority of genetic problems.
There are thousands of genetic diseases caused by mutations within genes, and these cannot be identified simply by counting chromosomes. So even if an embryo is labeled as “chromosomally normal,” that does not mean it is genetically perfect.
This is why the term PGD can be misleading. It creates the impression that we are performing a full genetic diagnosis when in reality we are doing something much more limited.
The Need for Prenatal Diagnosis Still Remains
This limitation becomes very clear when we look at what happens later in pregnancy.
Even when patients have undergone PGD or PGS during IVF, doctors still recommend prenatal diagnosis (PND) once the woman becomes pregnant. Prenatal diagnosis includes tests such as:
- Chorionic villus sampling (CVS)
- Amniocentesis
- Advanced prenatal screening tests
These tests are performed during pregnancy to check whether the baby is genetically normal.
If PGD truly provided a complete genetic diagnosis, prenatal testing would not be necessary. But the fact that we still need prenatal diagnosis highlights an important point:
PGD does not replace prenatal testing.
This means that the additional value provided by PGD in many IVF cases becomes quite limited.
Why Many Clinics Promote PGD Aggressively
Despite these limitations, PGD is heavily promoted in the IVF industry.
There are several reasons for this.
First, the concept is extremely appealing. Both doctors and patients like the idea of selecting the “best embryo.” It feels reassuring to believe that advanced technology can help eliminate uncertainty.
Second, the test adds another layer of sophistication to IVF treatment. Many clinics like to present themselves as using the latest cutting-edge technology, and PGD sounds very high-tech.
And third, it is an additional procedure that increases the cost of treatment.
None of this means that PGD is useless. It can be extremely valuable in specific situations, such as when couples carry known genetic disorders that they want to avoid passing on to their child. In those cases, true PGD can help identify embryos that do not carry the disease.
But those situations are relatively uncommon.
Why We Don’t Offer PGD Routinely
Because the benefits are limited for most patients, PGD is not something we offer routinely to all our IVF patients.
IVF already involves many complex decisions, and our goal is to help patients make choices that are truly evidence-based rather than driven by hype.
While PGD can sometimes provide useful information, it is important for patients to understand what the test can and cannot do. It does not guarantee a healthy baby. It does not eliminate the need for prenatal testing. And it does not dramatically increase success rates for every patient.
The Bottom Line
The idea behind PGD is intuitively attractive. Testing embryos before transfer sounds like a powerful way to improve IVF outcomes.
But the reality is that most of what is called PGD today is simply chromosome counting, not a comprehensive genetic diagnosis.
That is why even after PGD, patients still require prenatal diagnosis during pregnancy, and why the additional benefit of this testing is often more limited than many people expect.
As with every aspect of IVF treatment, the key is clear information and realistic expectations. When patients understand the true strengths and limitations of PGD, they can make decisions that are right for them—without being misled by terminology or marketing hype. For direct advice, you can get information to any query related to your IVF treatment from Dr Malpani instantly at https://www.drmalpani.com/chat-w-chatbot/index.html