Fertility genetics · London
PGT-A embryo screening, explained honestly before you commit.
Pre-implantation Genetic Testing for Aneuploidy (PGT-A) screens IVF embryos for whole-chromosome errors before transfer. Powerful for the right patient. Overhyped for many others. We help you tell which you are, then introduce you to the HFEA-licensed London clinic that fits your case.
What PGT-A actually is
A chromosome count, taken from the future placenta.
On day 5 or 6 of embryo culture, five to ten cells are biopsied from the trophectoderm - the outer layer that becomes the placenta. The inner cell mass, which becomes the baby, is left untouched. Each embryo is vitrified while next-generation sequencing analyses all 24 chromosomes for trisomy, monosomy or mosaicism. A result takes 5 to 10 days. Only euploid embryos (or, after counselling, selected low-level mosaics) are transferred in a later frozen cycle.
Not the same test
PGT-A screens for chromosome count. PGT-M looks for known single-gene diseases such as cystic fibrosis. PGT-SR is for carriers of a balanced translocation. Many clinics run PGT-A alongside one of the others - they answer different questions.
When PGT-A helps
Six situations where the evidence is strongest.
For low-risk younger patients doing their first IVF cycle, randomised trials (including STAR 2019) have not shown a per-transfer live-birth advantage. Benefit becomes clearer in these groups.
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Advanced maternal age (>35, strongest evidence >37)
Aneuploidy risk rises sharply with age. PGT-A can shorten time to a healthy live birth by prioritising euploid embryos for transfer.
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Recurrent implantation failure
Two or more failed transfers of good-quality embryos. PGT-A helps exclude chromosomal aneuploidy as the cause.
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Recurrent pregnancy loss
Two or more miscarriages, particularly where prior products of conception were aneuploid.
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Prior aneuploid pregnancy
A previous trisomy 21, 18 or 13 pregnancy - PGT-A screens the 24 chromosomes to reduce recurrence risk.
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Severe male factor with abnormal karyotype
Where sperm quality or a paternal karyotype raises the aneuploidy risk.
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Balanced translocation carriers
Overlaps with PGT-SR (structural rearrangements). A combined workup is usually recommended.
The evidence, honestly
Better per-transfer, unclear per-cycle.
PGT-A reliably reduces the miscarriage rate per transfer and can shorten time to a live birth in women over 37. The STAR trial (2019) and subsequent RCTs did not show a significant per-cycle live-birth improvement in unselected IVF patients - a euploid embryo transferred is the same as an untested embryo that would have been euploid. The advantage is faster selection, not more embryos.
The mosaicism nuance
Fifteen to twenty per cent of embryos are mosaic.
A mosaic embryo contains a mix of chromosomally normal and abnormal cells. Embryos once discarded on this basis have gone on to produce healthy babies. Since PGDIS 2021 guidelines, selective transfer of low-level mosaics is accepted after genetic counselling. Make sure your clinic has a written mosaic policy and offers you a counselling session before the biopsy, not after.
A PGT-A cycle, in order
From first consultation to a frozen transfer.
A full cycle is typically eight to twelve weeks. The frozen transfer usually follows the month after the result is back.
- 01
Before
Comprehensive fertility workup
Karyotype for both partners, ovarian reserve (AMH + antral follicle count), semen analysis, uterine imaging and a full ART cycle plan.
- 02
Before
Genetic counselling
A specialist counsellor explains what PGT-A can and cannot tell you, mosaicism, no-result rates and the cost of multiple cycles.
- 03
In cycle
Ovarian stimulation and egg collection
Ten to fourteen days of injections, monitored by scan and bloods. Egg collection under sedation.
- 04
In cycle
Fertilisation and blastocyst culture
ICSI or IVF fertilisation. Embryos grown to day 5 or 6 blastocyst stage.
- 05
In cycle
Trophectoderm biopsy
Five to ten cells are removed from the outer trophectoderm layer, preserving the inner cell mass. Embryos are vitrified while awaiting the result.
- 06
After
NGS analysis, 5 to 10 days
Next-generation sequencing analyses all 24 chromosomes for aneuploidy, mosaicism and copy-number variation.
- 07
After
Frozen embryo transfer
A euploid embryo is selected for a medicated or natural-cycle transfer, usually in the following month.
Compared to
The alternatives, so you can choose.
PGT-A is one option in a broader fertility plan. Sometimes it is right. Sometimes another route is more likely to give you a baby faster.
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Natural-cycle or unscreened IVF
Cheaper per cycle, no biopsy risk. Higher per-transfer miscarriage rate in women over 37, so more transfers may be needed.
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PGT-M (monogenic disease)
A different test for single-gene disorders such as cystic fibrosis or Huntington disease. Often run alongside PGT-A.
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PGT-SR (structural rearrangements)
For known translocation or inversion carriers. Detects unbalanced products missed by PGT-A alone.
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Donor-egg IVF
For severely diminished ovarian reserve or advanced maternal age where own-egg PGT-A yields few euploid embryos.
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Non-invasive PGT (niPGT)
Analysing spent culture media rather than biopsying the embryo. Promising research, not yet validated for clinical decisions.
Indicative pricing
What a PGT-A cycle actually costs.
Self-funded ranges at HFEA-licensed London clinics. Insurance rarely applies. Some clinics bundle refund or multi-cycle packages.
| Item | Indicative range | Note |
|---|---|---|
| Base private IVF cycle | £5,500-£8,500 | Consultations, monitoring, egg collection, lab, transfer. |
| Stimulation medications | £1,500-£2,500 | Varies with protocol and ovarian response. |
| PGT-A add-on (biopsy + NGS + vitrification) | £2,400-£4,500 | Priced per cycle, not per embryo, at most HFEA clinics. |
| Frozen embryo transfer (FET) | £1,600-£3,000 | Medicated or natural-cycle protocol. |
| Total PGT-A cycle (typical) | £9,500-£16,500 | Multiple cycles may be needed, particularly over 40. |
| Genetic counselling session | £180-£350 | Essential before consenting to PGT-A. |
Budget for the possibility of a second cycle, particularly if you are over 40 or have low ovarian reserve. Ask each clinic for its cumulative live-birth data by age band, not just per-transfer figures.
HFEA-licensed London providers
The London clinics that offer PGT-A.
HFEA-licensed centres with in-house PGT-A labs or partnerships with Cooper Genomics, Igenomix or Fertility Genomics. We introduce you privately once we understand your case.
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The Lister Fertility Clinic
Chelsea
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CARE Fertility London
Marylebone
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The Bridge Centre
London Bridge
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ARGC
Wimpole Street
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TFP The Fertility Partnership
Central London
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King's College Hospital Assisted Conception (Private)
Denmark Hill
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The Centre for Reproductive & Genetic Health
Fitzrovia
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Guy's and St Thomas' Assisted Conception (Private)
London Bridge
Frequently asked
The questions patients ask first.
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Does PGT-A guarantee a healthy baby?
No. PGT-A screens for chromosomal aneuploidy (trisomy, monosomy) across all 24 chromosomes. It does not detect single-gene disorders, structural birth defects, or every genetic condition. Standard antenatal screening still applies in pregnancy.
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Is PGT-A worth it if I am under 35?
The evidence is mixed. The STAR trial (2019) found no significant per-transfer live-birth improvement in an unselected IVF population. Benefit is clearer over 37 or after multiple failed cycles. Your specialist should discuss this honestly.
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What happens if an embryo is reported as mosaic?
Roughly 15 to 20 per cent of biopsied embryos return a mosaic result. PGDIS 2021 guidelines allow selective transfer of low-level mosaic embryos after genetic counselling, and healthy babies have been born from them. Your clinic should have a written mosaic policy.
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Is the trophectoderm biopsy safe for the embryo?
Only cells from the outer trophectoderm (future placenta) are removed. Large registry data suggest no meaningful reduction in implantation or live-birth rates when the biopsy is performed by an experienced embryologist.
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Will insurance cover PGT-A?
UK private medical insurance rarely covers IVF or PGT-A. A minority of employer schemes include a fertility benefit. Self-funding is the norm and clinics offer package pricing and finance.
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Do I have to use a London clinic?
No. Any HFEA-licensed centre with an in-house PGT-A lab or a partnership with Cooper Genomics, Igenomix or Fertility Genomics can offer it. We match you to the clinic whose protocols and results best fit your case.
Talk to a clinician, free
Not sure whether PGT-A is right for you? We will say honestly.
Send us your age, cycle history and any prior IVF results. Within one working day we come back with a plain-English view - whether PGT-A is likely to help, which HFEA-licensed London clinic fits your case, and indicative cost.
Reply within one working day. No sales calls.