PGD and PGS Treatment: Who Needs It and How It Fits Into IVF

Many couples arrive at their first consultation having read that testing embryos before transfer is the key to a healthy pregnancy. The reality is more nuanced. PGD and PGS treatment is a valuable tool for some families, an optional extra for others, and unnecessary for many. It is always performed as part of an IVF cycle, so if you are weighing up PGD and PGS treatment as part of IVF, the first question is not “which test?” but “does our situation actually call for one?” This article walks through who needs embryo testing, how it changes the steps of your cycle, and what Indian law permits.

From PGD and PGS to PGT: what the new names mean

The older terms are still widely used in India, but specialists now group all embryo testing under the umbrella of pre-implantation genetic testing (PGT). The new names are more precise about what each test is looking for:

• PGT-M (monogenic) — what used to be called PGD. It looks for one specific single-gene condition already known to run in the family, such as beta-thalassaemia, sickle cell disease, spinal muscular atrophy or cystic fibrosis.
• PGT-SR (structural rearrangement) — also a form of PGD. It is used when one partner carries a balanced translocation or inversion, which can produce embryos with missing or extra pieces of chromosomes.
• PGT-A (aneuploidy) — what used to be called PGS. It screens embryos for an abnormal number of whole chromosomes, the most common reason embryos fail to implant or pregnancies miscarry, particularly as maternal age rises.

The distinction matters because the reasons for doing each test, and the strength of evidence behind it, are very different. Understanding PGT-A vs PGT-M is the first step to a sensible decision.

Who needs PGD and PGS treatment?

Think of the indications in three groups: clear medical reasons, situations where testing may help, and situations where it usually adds little.

Clear indications: a known genetic risk

• Both partners are carriers of the same recessive condition. In India, beta-thalassaemia carrier status is the classic example. Each pregnancy carries a one-in-four chance of an affected child, and PGT-M allows unaffected embryos to be chosen.
• One partner has, or carries, a dominant or X-linked condition confirmed by genetic testing — for example Huntington disease or Duchenne muscular dystrophy in the family.
• A previous child has been affected by a serious genetic disorder and the mutation has been identified.
• One partner carries a balanced chromosomal rearrangement, often discovered after repeated miscarriages and a karyotype blood test.

In each of these cases the precise genetic change must be known before treatment begins. The test is designed around that specific family, which is why preparation can take several weeks.

Situations where PGT-A may be discussed

• Women in their late 30s and 40s, in whom a larger share of embryos are chromosomally abnormal.
• Recurrent pregnancy loss after other causes have been investigated.
• Repeated failed transfers of good-quality embryos.
• Couples who want to transfer a single embryo and would like more information to choose which one goes first.

Here the evidence is genuinely debated. PGT-A can reduce the number of transfers and miscarriages some couples go through, but large trials have not shown that it increases the overall chance of a baby from an egg collection for every patient. It may also lead to good embryos being discarded because of mosaic or inconclusive results.

When testing usually adds little

Younger women with good ovarian reserve, couples doing their first IVF cycle without any genetic history, and couples with only one or two embryos may gain very little and spend more. Embryo testing is not a fix for poor egg quality: it can identify abnormal embryos, but it cannot create normal ones.

How embryo testing fits into an IVF cycle

PGT does not replace any step of IVF; it adds a few. A typical sequence looks like this:

1. Genetic counselling and work-up. For PGT-M or PGT-SR, both partners’ reports are reviewed and the testing laboratory prepares a test specific to the family. Blood samples from relatives may be requested.
2. Ovarian stimulation and egg collection, exactly as in standard IVF. Because some embryos will not be suitable, the aim is usually to obtain a reasonable number of eggs.
3. Fertilisation, often by ICSI. Injecting a single sperm reduces the risk of stray sperm DNA contaminating the sample.
4. Culture to day 5 or 6. Embryos are grown to the blastocyst stage, which is why blastocyst culture is central to modern PGT.
5. Biopsy. An embryologist removes a few cells from the outer layer (trophectoderm), which goes on to form the placenta. The inner cell mass, which becomes the baby, is not touched.
6. Freeze-all. Every biopsied embryo is vitrified while the samples are analysed, which usually takes one to three weeks.
7. Results and counselling. You meet your doctor to go through which embryos are suitable for transfer.
8. Frozen embryo transfer in a later cycle, usually of a single embryo.

Your Ridge IVF consultant will tell you whether PGT is advisable and how testing is arranged with an accredited genetics laboratory. The embryology steps — culture, biopsy and freezing — take place in the IVF lab, while the genetic analysis itself is performed by that specialist laboratory.

Comparing the three types at a glance

For a deeper look at how the laboratory actually reads embryo DNA, what mosaic embryos are, and how accurate results are, see our companion article on PGD and PGS genetic testing explained.

What embryo testing cannot promise

It is important to go in with realistic expectations:

• It does not guarantee a pregnancy. A chromosomally normal embryo still may not implant, because implantation also depends on the uterus, embryo quality and factors we cannot yet measure.
• Some cycles produce no transferable embryo. This is emotionally hard, but it can also spare a couple an unsuccessful transfer or miscarriage.
• PGT-M tests only for the condition it was designed for. It is not a screen for every genetic disease.
• Results are not perfect. Because only a few cells are tested, prenatal testing during pregnancy is still advised to confirm results.
• The biopsy and freeze-all add cost and time, and a frozen transfer means at least one more month before you can be pregnant.

The legal limits in India: no sex selection

Embryo testing in India is governed by the Assisted Reproductive Technology (Regulation) Act, 2021. The Act permits pre-implantation genetic testing to screen embryos for known, pre-existing genetic diseases. It strictly prohibits selecting embryos by sex, and the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act also makes sex determination and selection a punishable offence. No reputable clinic will disclose or choose an embryo’s sex, and you should be wary of anyone who offers to.

The Act also requires that clinics and ART banks be registered on the national registry, which you can check on the ART and Surrogacy portal. Written informed consent is taken before any embryo testing, and unused embryos are managed according to the choices you record.

Questions to ask before you decide

• Is there a specific genetic diagnosis in our family, and has it been confirmed by testing?
• What is the realistic chance of having at least one suitable embryo at my age and ovarian reserve?
• Would PGT-A change our overall chance of a baby, or mainly the number of transfers?
• How will mosaic or inconclusive results be handled?
• Which accredited laboratory will analyse the samples, and how long do results take?
• What happens if no embryo is suitable for transfer?

A good consultant will answer these openly and will be just as comfortable advising you against testing as recommending it. Our fertility specialists are used to having these conversations with couples carrying thalassaemia trait, families with a known chromosomal rearrangement and women in their 40s alike.

Talk to a Ridge IVF specialist

If you have a family history of a genetic condition, recurrent miscarriages or repeated failed transfers, bring your reports and let us review whether embryo testing makes sense for you, and how it would fit into your IVF plan. You can book a consultation at our Jawahar Nagar, Fortis Shalimar Bagh or Burari centres, or call or WhatsApp +91 88001 00326.

This article is for general information and is not a substitute for a personal consultation with a fertility specialist.