World IVF Day 2026: How Genetic Testing Is Improving IVF Success Rates?

When the first baby born via IVF made history in 1978, the ultimate milestone was proving that clinical conception outside the human body was possible. Decades later, the focus has evolved beyond achieving fertilisation to selecting the embryo with the highest potential for a successful pregnancy. For many individuals and couples, the fertility journey is filled with complex decisions.

Genetic testing during IVF offers a powerful tool to bring clarity to that process. By screening embryos for chromosomal abnormalities and single-gene disorders, genetic testing helps clinicians optimise IVF outcomes while reducing the emotional and physical toll of failed cycles.

How Has IVF Evolved Since the Birth of the First IVF Baby?

By the mid-2000s, refinements in fertilisation, culture, and transfer made IVF safe and efficient.²  Early embryo selection relied strictly on microscopic visual appearance. The introduction of comprehensive chromosome analysis revolutionised the field, enabling direct assessment of an embryo’s chromosomal makeup rather than inferring potential from appearance alone.

Understanding IVF And Its Success Rates

In vitro fertilisation (IVF) is a process where an egg is fertilised by sperm in a lab, and the resulting embryo is placed into the uterus.^1,2

While average live birth rates range from 40%-50% for women under 35, success drops significantly with age, falling below 15% after age 40.³

Genetic testing during IVF is performed to evaluate an embryo’s genetic health before it is transferred to the uterus. It provides insights into an embryo’s chromosomal complement or specific genetic variants that cannot be detected under a microscope.⁴

Depending on the clinical indication, Preimplantation Genetic Testing (PGT) can identify chromosomal abnormalities, structural chromosomal rearrangements, or inherited single-gene disorders. This critical genetic data empowers clinicians to select the healthiest embryos, enabling personalised treatment strategies that boost the likelihood of a successful pregnancy while significantly lowering the risks of pregnancy loss or passing on genetic conditions.⁴

Preimplantation Genetic Testing (PGT) Explained

Preimplantation genetic testing, or PGT, checks an embryo’s chromosomes/DNA before it is transferred into the uterus. Here is how the process works:

• Growing the Embryo (Day 5 or 6): Doctors wait until the embryo reaches the blastocyst stage, an advanced stage where it has grown to about 100 cells, rather than testing it earlier when it has only a few cells (the cleavage stage).⁵
• Taking a Safe Biopsy: A specialist carefully removes 3 to 5 cells from the embryo’s outer layer (which forms the placenta), leaving the inner cells that develop into the baby completely untouched.⁶
• Lab Analysis & Freezing: The embryo is safely frozen while the removed cells are sent to a lab to analyse their chromosomes or genes.⁵
• Embryo Selection: Once results are back, clinicians select the healthiest embryo to thaw and transfer, maximising your chance of a successful pregnancy.⁵

Types Of PGT Used In IVF

Because every fertility journey is unique, different types of Preimplantation Genetic Testing (PGT) address different genetic risks.

PGT-A: Screening For Chromosomal Abnormalities

Here is what you need to know about PGT-A (Preimplantation Genetic Testing for Aneuploidy):

• What it is: A general screening tool that checks all 24 chromosomes in an embryo for extra or missing chromosomes, a condition called aneuploidy, which is the leading cause of early pregnancy loss.⁵
• What it detects: Numerical errors like Down syndrome (Trisomy 21), Turner syndrome, or random chromosomal extra/missing copies.⁵
• Who it is recommended for: Women of advanced maternal age (typically 35 and older), couples with a history of recurrent miscarriages, or those who have had multiple failed IVF cycles.⁵
• Key Consideration (Mosaicism): PGT-A results sometimes reveal mosaic embryos, which contain a mix of normal and abnormal cells. Many mosaic embryos can self-correct and result in healthy pregnancies, so patients should ensure their clinic has clear guidelines regarding mosaic embryo transfers rather than automatically discarding them.⁵

PGT-M: Testing For Single-Gene Disorders

• What it is: A targeted test used when parents are at high risk of passing down a specific, inherited genetic condition caused by a single mutated gene.⁷
• What it detects: Specific inherited conditions such as Cystic Fibrosis, Sickle Cell Anaemia, Thalassemia, Huntington’s Disease, or hereditary cancer genes like BRCA1/BRCA2.⁷
• Who it is recommended for: Couples known to be carriers of a genetic mutation.⁷ These maybe identified by testing an affected individual or through carrier screening.
• The Role of Carrier Screening: PGT-M is made possible through pre-conception carrier screening, a routine blood or saliva test taken before starting IVF. Carrier screening identifies whether you or your partner carry silent genetic mutations (such as Cystic Fibrosis or Spinal Muscular Atrophy). If both partners carry a mutation for the same condition, PGT-M is then designed to test the embryos for that specific gene variant before transfer.⁸

PGT-SR: Detecting Structural Rearrangements

• What it is: A test designed for individuals who carry a structural rearrangements in their own chromosomes, such as pieces of chromosomes being swapped or flipped (translocations or inversions).⁶
• What it detects: Embryos with missing or duplicated genetic material caused by inheriting an “unbalanced” version of a parent’s chromosomal rearrangement.⁶
• Who it is recommended for: Individuals or couples where a parent has been diagnosed via blood karyotype testing with a balanced translocation or inversion. While these parents are usually completely healthy, their embryos face a high risk of unbalanced genetic material, leading to failed implantation or early miscarriage.⁶

How Does PGT Improve IVF Success Rates?

Helps Select The Healthiest Embryo For Transfer

The way an embryo looks under the microscope does not always reflect its genetic health. Even an embryo that appears healthy may have chromosomal abnormalities. Genetic testing provides information that cannot be seen through appearance alone. While it cannot guarantee which embryo will lead to a successful pregnancy, it helps identify embryos that are less likely to implant or develop into a healthy pregnancy.⁵

Reduces Miscarriage And Failed Implantation

Most first-trimester losses are chromosomal in origin, which gives a clear biological rationale for screening.⁵  In a retrospective study of single embryo transfers, the group screened by comprehensive chromosome analysis had an ongoing pregnancy rate of 55.0% against 41.8% in unscreened controls, with miscarriage in 10.5% versus 24.8% of clinical pregnancies.⁴

Enables Safe Single Embryo Transfer

Transferring several embryos to improve the odds carries a real cost: multiple pregnancy is the principal issue of IVF and raises risk for mother and babies alike.⁴ Identifying a single euploid embryo supports elective single embryo transfer without a corresponding fall in success per cycle. This is the clearest and best-established benefit of the technology. ⁵

Who Should Consider Genetic Testing During IVF?

Genetic testing in IVF is elective and requires informed consent, including a discussion of the option not to test.⁵ It is most often considered by women of advanced maternal age, couples with recurrent pregnancy loss, and those with a known inherited condition or balanced rearrangement in the family. Where a serious monogenic disorder runs in a family, PGT-M is strongly recommended and should be preceded by genetic counselling.⁷

Benefits And Limitations Of Genetic Testing In IVF

Benefits

• Supports Safe Single Embryo Transfer: Identifying a chromosomally normal embryo gives clinical teams the confidence to transfer one embryo at a time. This significantly reduces the medical risks associated with multiple pregnancies (twins or triplets) without compromising the success rate per transfer.⁵
• Optimises Time to Pregnancy & Reduces Loss: By selecting embryos with the highest potential first, genetic screening can shorten the journey to a successful pregnancy and lower the risk of early miscarriages, a crucial emotional and physical advantage for patients.⁵

Limitations

• Tailored Clinical Utility: Large-scale studies show that the benefits of universal screening (PGT-A) vary by age and diagnosis. While young, good-prognosis patients may achieve strong cumulative pregnancy rates without routine screening, PGT-A offers significant targeted advantages for women of advanced maternal age or those with a history of recurrent pregnancy loss.⁹, ¹⁰
• Embryo Yield & Technical Considerations: Genetic testing requires embryos to reach the blastocyst stage (Day 5/6) for a biopsy. Because not every retrieved egg or fertilised embryo makes it to this stage, clinicians evaluate each patient’s individual yield to determine if biopsy is the right strategy.⁵

Why Genetic Counselling Is Important in Your IVF Journey

Genetic counselling is vital throughout IVF, helping patients make informed choices before and after testing.

• Before testing: Counsellors explain benefits, limitations, inconclusive or mosaic results, misdiagnosis risks, and the option to forgo testing.⁵
  
• After testing: They clarify results to guide treatment decisions.⁵

Professional guidelines recommend access to counselling at every stage to ensure clear, supported decisions.

The Future Of Genetic Testing And IVF

The future of genetic testing in IVF points toward non-invasive approaches that analyse DNA released into the culture medium, avoiding biopsy altogether. However, these are not yet validated for clinical use. The realistic near-term picture is more targeted use of PGT in the patients most likely to benefit, rather than universal adoption.⁵

To navigate this evolving landscape,MedGenome supports clinical teams and patients with comprehensive preimplantation and carrier genetic testing, backed by expert genetic counselling.

FAQ’s

1. How does genetic testing improve IVF success rates?
   Its clearest benefit is enabling single embryo transfer, since identifying a euploid embryo allows one to be transferred without reducing the chance of pregnancy. This helps avoid the risks of twin and triplet pregnancy. Evidence that PGT-A raises cumulative live birth rates for all patients is mixed, and current professional guidance does not support routine use in every IVF cycle.
2. What is preimplantation genetic testing (PGT)?
   PGT is the analysis of a small number of cells taken from an embryo on day five or six of development, before transfer. Depending on the test, it examines chromosome number, a specific inherited gene variant, or a structural chromosomal rearrangement.
3. What is the difference between PGT-A, PGT-M and PGT-SR?
   PGT-A assesses chromosome copy number to identify missing or extra chromosomal material. PGT-M tests for a specific inherited condition known to be in the family. PGT-SR identifies unbalanced material in embryos of parents carrying a balanced rearrangement such as a translocation.
4. Does PGT guarantee a successful pregnancy?
   No. PGT provides information about the embryo’s genetic status, but implantation and live birth also depend on endometrial receptivity, maternal health and factors that are not yet well understood. Results can also be inconclusive or mosaic, which is why they should be interpreted with a clinician or genetic counsellor.

References

1. Williams, Clare. “Looking into the Test Tube: The Birth of IVF on British Television.” Medical History 63, no. 2 (2019). https://pmc.ncbi.nlm.nih.gov/articles/PMC6434648/
2. Wang, Jeff, and Mark V. Sauer. “In vitro fertilization (IVF): a review of 3 decades of clinical innovation and technological advancement.” Therapeutics and Clinical Risk Management 2, no. 4 (2006): 355–64. https://pmc.ncbi.nlm.nih.gov/articles/PMC1936357/
3. Tan, Tse Yeun, Matthew Sie Kuei Lau, Seong Feei Loh, and Heng Hao Tan. “Female ageing and reproductive outcome in assisted reproduction cycles.” Singapore Medical Journal 55, no. 6 (2014): 305–309. https://pmc.ncbi.nlm.nih.gov/articles/PMC4294057/
4. Forman, Eric J., Xin Tao, Kathleen M. Ferry, Deanne Taylor, Nathan R. Treff, and Richard T. Scott Jr. “Single embryo transfer with comprehensive chromosome screening results in improved ongoing pregnancy rates and decreased miscarriage rates.” Human Reproduction 27, no. 4 (2012): 1217–22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3303493/
5. Practice Committee of the American Society for Reproductive Medicine. “The use of preimplantation genetic testing for aneuploidy: a committee opinion.” Fertility and Sterility 122, no. 3 (2024): 421–34. https://www.asrm.org/practice-guidance/practice-committee-documents/the-use-of-preimplantation-genetic-testing-for-aneuploidy-a-committee-opinion-2024/
6. ESHRE PGT-SR/PGT-A Working Group; Coonen, Edith, Carmen Rubio, Dimitra Christopikou, et al. “ESHRE PGT Consortium good practice recommendations for the detection of structural and numerical chromosomal aberrations.” Human Reproduction Open 2020, no. 3 (2020): hoaa017. https://academic.oup.com/hropen/article/2020/3/hoaa017/5848300
7. Practice Committee of the American Society for Reproductive Medicine. “Indications and management of preimplantation genetic testing for monogenic conditions: a committee opinion (2023).” https://www.asrm.org/practice-guidance/practice-committee-documents/indications-and-management-of-preimplantation-genetic-testing-for-monogenic-conditions-a-committee-opinion-2023/
8. American College of Obstetricians and Gynecologists. “Carrier Screening in the Age of Genomic Medicine.” Committee Opinion No. 690. Obstetrics & Gynecology 129, no. 3 (2017): e35–e40. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/03/carrier-screening-in-the-age-of-genomic-medicine
9. Munné, Santiago, Brian Kaplan, John L. Frattarelli, et al. “Preimplantation genetic testing for aneuploidy versus morphology as selection criteria for single frozen-thawed embryo transfer in good-prognosis patients: a multicenter randomized clinical trial.” Fertility and Sterility 112, no. 6 (2019): 1071–1079.e7.
   https://pubmed.ncbi.nlm.nih.gov/31551155/
10. Yan, Junhao, Yingying Qin, Han Zhao, et al. “Live Birth with or without Preimplantation Genetic Testing for Aneuploidy.” New England Journal of Medicine 385, no. 22 (2021): 2047–2058. https://www.nejm.org/doi/full/10.1056/NEJMoa2103613