Researchers in a 2019 study performed a clinical trial among good prognosis women aged 25-40 on the effectiveness of PGT-A vs embryo grading, finding no difference.
During IVF, embryos can be selected for transfer based on how they look. Different grades can be assigned and the prettier the embryo, the higher the potential for a pregnancy.
Another selection tool has been PGT-A, where the embryo is biopsied and then analyzed for aneuploidy. Embryos with the correct number of chromosomes are dubbed euploid and are thought to have a higher potential compared to embryos with the incorrect number of chromosomes (aneuploid).
The use of PGT-A has been controversial and studies still go on to confirm whether or not it actually increases success rates.
Check my complete guide to PGT-A to get more background on PGT-A (aka PGS testing).
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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A study by Munne et al. (2019) aimed to look at how traditional embryo grading compares to PGT-A, in the context of a good prognosis (25-40 years old, at least 2 blasts available for biopsy, no diminished ovarian reserve). The single best embryo by grading was frozen to be transferred in the grading group, while the euploid with the best grade was transferred in the PGT-A group.
The results came from 34 different clinics and 9 different PGT testing labs around the world (2014 to 2016). A total of 661 patients were part of this study with 331 as control (no PGT-A ) and 330 (with PGT-A).
Here’s what they found!
For women aged 25-40 there was no significant difference in ongoing pregnancy rates with PGT-A (50.0%) vs without PGT-A (45.7%). There were also no differences in miscarriage (9.9% vs 9.6%). These differences were not significant for both the intention-to-treat analysis, which means that the overall clinical trial showed no improvement of PGT-A over traditional embryo grading for women 25-40.
Then they analyzed the data again and broke it down by age groups:
- For 25-34: no difference in ongoing pregnancy rates (49.3% with PGT-A vs 53.0% without)
- For 35-40: increase in ongoing pregnancy rates (50.8% with PGT-A vs 37.2% without)
- No differences in miscarriage rates in both groups
Note that by manipulating the data by age group, which was not how the clinical trial was originally designed, reduces the overall quality of this evidence since it introduces bias into the reporting. This is not ideal and further studies need to be done to confirm that this age group truly benefits.
Some clinics will not recommend PGT-A testing unless it is warranted – repeated miscarriage or advanced age (>35) – while others will insist on testing for all patients. This study shows that PGT-A is not effective over conventional grading for good prognosis women aged 25-40.
Even though conventional grading may select an embryo just as well as PGT-A in some cases, a benefit of PGT-A is identifying which embryos are aneuploid. Aneuploid embryos have a very low chance of producing a live birth, so even in younger women PGT-A may be desirable.
Reference
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About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.
Related posts:
Complete guide to PGT-A (PGS testing)
PGS (PGT-A) success rates
Study examines potential of day 7 euploid transfers
PGT-A vs embryo grading: results of a 2021 clinical trial.
Aneuploid-only first PGT-A cycle has no impact on future PGT-A outcomes
Multiple embryo freeze/thaw for PGT-A doesn’t affect pregnancy or neonatal outcomes
A look at how PGT-A results change with age, using data from over 86,000 biopsies
Study compares PGT-A outcomes for patients with different diagnoses