PGT-A Testing IndiaThe World's Most Comprehensive Patient Guide to Your Genetic Report

PGT-A — Preimplantation Genetic Testing for Aneuploidies — analyses the chromosomes of an embryo before it is transferred into the uterus. The goal is to identify embryos with a normal complement of chromosomes (46 chromosomes — euploid) so that only chromosomally normal embryos are selected for transfer.

PGT-A is performed on a Day 5 or Day 6 blastocyst using trophectoderm biopsy — where 5–8 cells are carefully removed from the outer cell layer of the embryo without disturbing the inner cell mass (which becomes the baby). These cells are sent to a genetics laboratory for chromosomal analysis using Next Generation Sequencing (NGS).

PGT-A is most beneficial in: advanced maternal age (above 35), recurrent miscarriage, repeated IVF failure, known chromosomal issues in either partner, or when the couple wants to maximise the chance of a successful first transfer. PGT-A does not make embryos better — it identifies which existing embryos are already chromosomally normal.

Euploid means the embryo has the correct number of chromosomes — 46 in total, arranged as 23 pairs. An euploid embryo is, from a chromosomal standpoint, normal.

• This embryo can be transferred — it has passed the chromosomal quality screen
• Approximately 60–70% implantation rate per transfer at experienced centres
• Approximately 5–8% miscarriage rate after confirmed euploid FET (vs 20–30% without PGT-A)
• Does not carry a chromosomal condition detectable by PGT-A

What euploid does NOT guarantee: an euploid result does not guarantee implantation — other factors including endometrial receptivity, embryo grade, and non-chromosomal factors still influence outcomes. It does not screen for gene-level mutations. All PGT-A pregnancies should still have standard prenatal screening.

Aneuploid means the embryo has an abnormal number of chromosomes — either too many (trisomy — one extra) or too few (monosomy — one missing). The majority of aneuploid embryos either fail to implant, implant and miscarry early, or in a small proportion result in a chromosomally affected birth such as Down syndrome (trisomy 21).

Why aneuploid results are so common in IVF: chromosomal aneuploidy increases dramatically with maternal age. At age 35 approximately 40–50% of blastocysts are aneuploid. At age 40, 60–70%. At age 42+, above 75%. This explains why IVF cycles sometimes fail despite apparently good-looking embryos. Aneuploid embryos should not be transferred — the international consensus recommendation is clear.

A mosaic embryo contains a mixture of two or more cell lines: some cells are euploid (46 chromosomes) and some cells are aneuploid. This mixture arises from an error in cell division after fertilisation — not a meiotic error in the egg or sperm. Because the error occurred after fertilisation, only some cells carry it.

Mosaic results are reported as a percentage: Low-level mosaic (20–40% abnormal cells) and High-level mosaic (40–80% abnormal cells). Above 80% is classified as aneuploid. The outcomes of mosaic transfer: lower implantation rates than euploid (~35–50% vs 60–70%); higher miscarriage rates; but the majority of babies born from mosaic transfers are chromosomally normal.

A 'no result' means the laboratory was unable to generate a valid chromosomal analysis from the biopsy sample. The embryo itself was not harmed. The failure was in the laboratory processing — not in the embryo. Options: (1) Re-biopsy — the embryo can be re-warmed and a fresh biopsy taken; success rate ~60–75%. (2) Transfer without result — treat as untested and transfer based on morphology. (3) Discard — if multiple euploid embryos are available. A 'no result' does NOT mean the embryo is abnormal.

PGT-A and PGT-M can be combined on the same trophectoderm biopsy for couples who have both a known genetic condition AND are doing IVF for age or infertility reasons.

PGT-A confirms chromosomal normalcy — it does not assess all other dimensions of embryo quality. A euploid embryo with a poor inner cell mass (grade C) has fewer cells that will form the foetus. Similarly, poor trophectoderm quality (grade C) affects placentation. The published data confirms that blastocyst grade independently predicts implantation rate among euploid embryos.

At Shree IVF Clinic, the role of MITOSCORE is strongly considered as part of the final embryo scoring — complementing both PGT-A result and morphological grade for the most informed transfer prioritisation decision.

A 3BC embryo has a lower implantation rate than a 4AA embryo — but 'lower' in the context of euploid transfers still represents a meaningful clinical probability. The chromosomal normalcy confirmed by PGT-A is the single most important factor for avoiding miscarriage. Morphological imperfection does not override genetic normalcy for the transfer decision.

When you have multiple euploid embryos, the prioritisation order is: (1) AA/5AA/6AA — highest priority; (2) AB or BA — second priority; (3) BB — third; (4) BC or CB — fourth; (5) CC — last. Day 5 euploid embryos have modestly higher implantation rates than Day 6 (~5–10% difference). Dr. Jay Mehta provides personalised prioritisation based on the complete picture of each embryo's grade, biopsy details, timelapse, and MITOSCORE.

Why euploid embryos sometimes miscarry: chromosomal mosaicism not fully detected by the biopsy; non-chromosomal genetic abnormalities (gene-level mutations PGT-A cannot see); poor endometrial receptivity; anatomical uterine factors (polyps, fibroids, septum); thrombophilia or immunological factors (antiphospholipid syndrome, elevated uNK cells). If a euploid transfer results in miscarriage, systematic investigation of these causes is the next step.

PGT-A is a chromosomal number screening test. What it does NOT detect: single gene mutations (requiring separate PGT-M); very small chromosomal deletions or duplications below ~5–10 Mb resolution; mitochondrial DNA abnormalities; epigenetic abnormalities. A euploid result provides strong reassurance about chromosome number — but does not replace first-trimester combined screening, NIPT, or anomaly scans at 18–20 weeks.

All-aneuploid results are one of the most devastating outcomes in IVF — and also one of the most common for women above 38–40. Aneuploidy rates increase from ~25–30% at age 30 to 70–80%+ at age 42. In a cycle producing 4–5 embryos for an older woman, all being aneuploid is biologically expected.

Options after all-aneuploid results:

• Another egg retrieval cycle: each cycle is independent — a second or third may produce euploid embryos
• Accumulation strategy: bank embryos from 2–3 cycles before any transfers
• Donor egg IVF: eggs from a young donor (23–30) have dramatically lower aneuploidy rates (~15–25%); live birth rates 50–65% per transfer regardless of recipient age
• Transfer the best-looking aneuploid embryo (last resort): success rate less than 5–10%; miscarriage risk 60–75%; requires extensive counselling and explicit consent

When embryos show more than 6 abnormalities simultaneously (chaotic aneuploidy), Whole Exome Sequencing for the couple is recommended to investigate any underlying genetic susceptibility.

'Self-correction' (aneuploidy rescue) has been documented in research but its clinical reliability is highly contested. The risk of transferring an aneuploid embryo based on hope of self-correction: failed implantation (most common); miscarriage; or chromosomally affected live birth. The exception: mosaic embryos — where only a proportion of cells are aneuploid — have genuine clinical potential for transfer under specific guidelines.

Fully aneuploid embryos (by validated NGS PGT-A) have a less than 5% chance of producing a live birth per transfer, and the risks include repeated miscarriage and chromosomally affected birth. However, the ethical and emotional dimension is real — some patients with strong religious or moral convictions about embryo disposition choose to keep aneuploid embryos in storage. At Shree IVF Clinic, Dr. Jay Mehta reviews every case individually before recommending embryo disposal.

Possible explanations for young women: Diminished Ovarian Reserve (DOR) — very low AMH regardless of age; eggs behave like an older woman's eggs. Premature Ovarian Insufficiency — accumulated meiotic errors. FMR1 premutation (fragile X carrier) — higher baseline aneuploidy at any age. Suboptimal stimulation response — recruiting smaller, less mature follicles. One-cycle bad luck — the stochastic nature of meiotic errors means one cohort can be unusually affected.

Recommendation for young women with all-aneuploid first cycles: comprehensive evaluation (AMH, AFC, FMR1 premutation testing, karyotype), then proceed with a second retrieval cycle with protocol modification before drawing long-term conclusions.

Think of it this way: imagine a mosaic embryo as a crowd of 100 people, of whom 70 are healthy and 30 are unwell. The crowd is neither perfectly healthy nor critically ill. The outcome depends on which individuals end up in the critical roles — specifically, whether the normal cell fraction dominates the inner cell mass (future foetus) lineage. The biological distinction from full aneuploidy is critical: a fully aneuploid embryo has the error in EVERY cell; a mosaic has it in only SOME cells.

The PGDIS registry of mosaic transfers found that among pregnancies from mosaic embryo transfer, the majority produced chromosomally normal babies. Prenatal testing of ongoing pregnancies showed normal results in approximately 77–85% of cases. The requirements before mosaic transfer: (1) No euploid embryos documented; (2) Specific pre-transfer genetic counselling; (3) Written informed consent; (4) Confirmed commitment to amniocentesis for any ongoing pregnancy.

Trophectoderm biopsy does carry a small but real risk of embryo damage — directly related to the skill and experience of the embryologist. Studies show that biopsy-related embryo attrition is significantly higher in centres performing fewer than 50–100 biopsies per year. A 1% vs 5% attrition rate sounds small, but if you have 4 embryos, the difference between 0.04 and 0.2 embryos expected to be lost is clinically meaningful. Shree IVF Clinic performs the maximum number of trophectoderm biopsies in India — protecting every embryo through the highest possible level of technical skill.

Mechanisms of false euploid: (1) The trophectoderm cells sampled were from the normal fraction while the ICM contains aneuploid cells; (2) Very low-level mosaicism below the 20% detection threshold; (3) Small segmental aneuploidies below ~5–10 Mb resolution. PGT-A is a 'screening' test, not a 'diagnostic' test — it substantially reduces chromosomal risk but does not eliminate it. This is why NIPT, first-trimester combined screening, and anomaly scans remain important after euploid transfers.

False aneuploid results occur when trophectoderm cells biopsied are aneuploid, but the inner cell mass (the future foetus) is predominantly euploid. This is called confined trophectoderm aneuploidy. Multiple studies show 5–15% of embryos classified as aneuploid by trophectoderm biopsy may have a normal ICM. At Shree IVF Clinic, Dr. Jay Mehta reviews every case individually — assessing the specific chromosome(s) involved, the biopsy quality, and the couple's complete clinical picture — before recommending embryo disposal.

Segmental aneuploidies differ from full chromosome aneuploidies in: clinical significance (varies by size and location); higher false positive rate (more likely to be a technical artefact); and potential for inherited origin (if the same segmental change appears in multiple embryos, parental chromosomal array testing should be considered). Very small segmental changes may be considered for transfer after specialist review, particularly in couples with no other options.

Detailed pathway: Mosaic transfer first (if any mosaics available — PGDIS framework applies). Then another retrieval with modifications: DHEA 25 mg/day + CoQ10 400 mg (ubiquinol) + Vitamin E + Vitamin D for 10–12 weeks pre-retrieval; consider growth hormone co-stimulation if ovarian reserve is reduced. Donor egg IVF achieves live birth rates of 50–65% per transfer regardless of recipient age — this is the highest-probability option for women above 40–42 with multiple all-aneuploid cycles. It is a medically informed pivot, not a failure.

The euploid embryo has: the highest per-transfer live birth rate (~60–70%); the lowest miscarriage rate (5–8%); the lowest risk of a chromosomally affected child; and no requirement for amniocentesis or additional prenatal testing beyond standard pregnancy monitoring. The mosaic embryos should never be transferred before a euploid embryo under any circumstances.

PGT-A is clearly recommended: maternal age above 35–37; recurrent miscarriage (2+ losses); repeated IVF failure (2+ failed transfers); known parental chromosomal translocation; strong preference for highest per-transfer success. PGT-A may not be routinely recommended: women under 33–34 with good ovarian reserve and no prior miscarriage/IVF failure — multiple RCTs have NOT shown improvement in cumulative live birth rates in this population; the benefit is efficiency, not ultimate probability.

At Shree IVF Clinic — India's highest-volume trophectoderm biopsy centre — Dr. Jay Mehta discusses PGT-A indication for every couple individually, not as a blanket recommendation.

PGT-A only tests chromosome number. Single gene mutations (cystic fibrosis, thalassaemia, sickle cell, Huntington, BRCA1/2) require PGT-M — a customised genetic probe developed specifically for the family's mutation. Combined PGT-A + PGT-M testing from a single trophectoderm biopsy is available at Shree IVF Clinic, Mumbai. Contact +91-9920914115 for a combined testing consultation.

Endometrial causes (most common): Displaced implantation window (~20–25% of unexplained failures) — ERA test identifies personalised timing for pET protocol. Chronic endometritis — found in ~15–30% of women with recurrent implantation failure, diagnosed by hysteroscopy or EMMA/ALICE test, treated with targeted antibiotics. Thin endometrium (below 7 mm) — G-CSF or PRP instillation. Uterine anatomical issues (polyps, fibroids, septum, adhesions) — hysteroscopy is gold standard for diagnosis and treatment.

Immunological causes: Elevated uterine natural killer cells — diagnosed by endometrial biopsy; treated with prednisolone or intralipid. Antiphospholipid syndrome — low-dose aspirin + LMWH. Sperm causes: High sperm DNA fragmentation (double-strand breaks) — testicular sperm ICSI may help if ejaculated DFI is high. Technical causes: Suboptimal thaw or transfer technique at low-volume centres.

For women above 35–38: without PGT-A, 50–70% of embryos are aneuploid and will be transferred before the euploid ones are reached, costing time, money, and emotional wellbeing. PGT-A selects the euploid embryo first, reducing total transfers needed. For young women under 33–34: the majority of embryos are already euploid (~60–75%), so PGT-A selects among them but the cumulative probability over 3–4 cycles is similar regardless. Multiple RCTs confirm no improvement in cumulative live birth rates in young, normal-responding women.

Not all IVF centres have the equipment (laser dissection systems) or embryologist expertise to perform trophectoderm biopsy safely. PGT-A at a low-volume biopsy centre carries higher embryo attrition risk and potentially higher 'no result' rates. The most important factor is that PGT-A is performed at a centre with sufficient biopsy volume to guarantee technical excellence. Shree IVF Clinic under Dr. Jay Mehta performs the maximum number of trophectoderm biopsies in India — the single most experienced trophectoderm biopsy centre in the country for PGT-A testing India.