Introduction

PGT-A | PGT-M | PGT-SR

Preimplantation genetic testing (PGT) is one of the most powerful advances in reproductive medicine - allowing us to assess embryos before pregnancy has begun. For many individuals and couples, PGT offers clarity where uncertainty exists: helping reduce the chance of passing on genetic illness, lowering miscarriage risk in selected cases, and supporting informed and intentional embryo selection.

I’m a CREI (sub-specialist in Reproductive Endocrinology & Infertility) trained Fertility Specialist, Gynaecologist with a clinical and academic focus on personalised IVF strategy, reproductive genetics, recurrent miscarriage, and complex fertility care. My approach combines precision laboratory science with compassionate, patient-centred decision-making. PGT is not designed to replace IVF-it enhances it when the indication is right. Understanding when it helps, and when it may not, is central to achieving the best possible outcomes for women, men, and families.

Whether you are navigating inherited disease risk, experiencing recurrent pregnancy loss, or seeking the most efficient pathway to a healthy pregnancy, this page is designed to guide you through the three types of PGT available:

• PGT-A - testing for chromosome number abnormalities (aneuploidy)

• PGT-M - testing for specific monogenic/single-gene conditions

• PGT-SR - testing for structural chromosomal rearrangements

What is Preimplantation Genetic Testing?

Preimplantation genetic testing is a technique used during IVF to assess the chromosomal or genetic make-up of embryos before they are transferred into the uterus. A small number of trophectoderm cells are biopsied from the embryo at the blastocyst stage, then analysed using advanced genomic technology. Only embryos identified as suitable for transfer are considered for pregnancy.

PGT does not create genetically healthy embryos—it helps us identify them when they exist. The goal is to improve reproductive outcomes in selected patients, reduce uncertainty, and provide greater confidence in embryo selection.

PGT-A

Preimplantation Genetic Testing for Aneuploidy

PGT-A screens embryos for chromosomal copy-number abnormalities (e.g. trisomy, monosomy). Aneuploid embryos have a lower implantation potential and a higher rate of miscarriage.

Most useful for:

• Maternal age-related aneuploidy risk

• Recurrent miscarriage or recurrent implantation failure

• Patients with multiple embryos wishing to optimise selection

• Previous pregnancy affected by chromosomal abnormality

Potential benefits

• Increased chance of selecting a chromosomally normal (euploid) embryo

• May reduce miscarriage risk in selected patients

• Supports safe single embryo transfer to minimise twins

• May shorten time to pregnancy when many embryos are available

Considerations & limitations

• Not beneficial for all IVF patients

• Mosaic results may require nuanced counselling

• A confirmed pregnancy still requires antenatal screening

PGT-M

Preimplantation Genetic Testing for Monogenic Disorders

PGT-M (formerly PGD) is used when there is a known single-gene condition in the family. A customised test is developed to identify embryos that do not carry the disease-causing variant.

Suitable for families where:

• Both partners carry the same autosomal recessive gene variant

• One partner has an autosomal dominant condition

• There is an X-linked condition at risk of affecting male offspring

• There is a strong family history of serious inherited disease

• An affected child already exists and recurrence is to be avoided

Key advantages

• Significantly reduces the chance of transmitting serious disease

• Can avoid the emotional difficulty of terminating an affected pregnancy

• Can be combined with PGT-A for further chromosomal assessment

Important notes

• A known pathogenic variant must be identified

• Test building may take several weeks to months

• Prenatal diagnostic testing is recommended even after PGT-M

PGT-SR

Preimplantation Genetic Testing for Structural Rearrangements

PGT-SR is used when one partner carries a balanced translocation or other chromosomal rearrangement. These individuals are typically well but have increased risk of miscarriage or having a child with unbalanced chromosomes.

Indications include:

• Known balanced translocation or inversion

• Recurrent pregnancy loss with parental chromosomal abnormality

• History of chromosomally unbalanced offspring

Benefits

• May reduce miscarriage risk

• Helps identify viable embryos with normal or balanced chromosomes

• Improves reproductive predictability and planning

Limitations

• Highly individualised test design

• Confirmatory CVS or amniocentesis still recommended

The PGT Process

How it works from consultation to embryo transfer

• Genetic counselling + personalised treatment planning

• IVF cycle, egg collection and fertilisation

• Blastocyst-stage embryo biopsy

• Genetic analysis via NGS or validated platform

• Embryo cryopreservation while results return

• Multidisciplinary review + embryo selection

• Frozen embryo transfer and pregnancy follow-up

My Approach: Expertise + Ethics + Individualised Care

PGT can be life-changing for the right patient-but it is not one-size-fits-all. Every PGT plan with me includes:

• Comprehensive risk-benefit counselling

• Joint decision-making around when testing is truly valuable

• Collaboration with geneticists, counsellors and advanced labs

• Continued antenatal genetic screening during pregnancy

• Emotional support, clarity and transparency throughout

“The real question isn’t whether testing is possible, but whether it will meaningfully improve your chance of having a healthy baby.”