P-540 Is there a necessity to process preimplantation genetic aneuploidy testing (PGT-A) of embryos in all patients undergoing Assisted Reproductive Technology (ART) programs?
Authors: Shishimorova M , Tevkin S , Jussubaliyeva T 
Published: June 2022

Abstract

Study question
Should each embryo undergo preimplantation genetic testing for aneuploidy (PGT-A), or a personalized approach following indications such as age should be applied?

Summary answer
PGT-A does not increase clinical pregnancy and live birth rates in women under 35, however results are significantly improved for female patients over 35 years.

What is known already
PGT is a powerful tool in standard IVF practice however, despite all the benefits of the technology, it remains one of the most controversial topics that continue to generate interest, discussion, and debate in the field of reproductive medicine. Proponents believe that the potential of PGT-A allows effectively selecting a euploid embryo based on its genetic status and achieving a result in a short time regardless of the patient's age. Opponents consider that PGT-A cannot reflect the chromosomal status of the entire embryo with 100% accuracy, and embryo manipulation is inherently invasive and traumatic, which may reduce the life-birth potential.

Study design, size, duration
The retrospective single-center study included 2164 ART cycles performed from 2017 to 2020 at the Institute of Reproductive Medicine, Almaty, Kazakhstan. Clinical pregnancy rates (CPR), live birth rates (LBR), and pregnancy losses were analyzed. Results of frozen embryo transfer (FET) cycles with PGT-A as Group A (n = 637), FET without PGT-A as Group B (n = 705) and fresh cycle transfer as Group C (n = 822) have been compared. Moreover, selection were categorized by female age: ≤35 and &gt;35.

Participants/materials, setting, methods
In the “fresh” IVF cycle (Group C), day 5 blastocysts of excellent/good quality according to the Gardner classification were selected for transfer. Trophectoderm (TE) biopsy of about 5-10 cells was performed on day 5/6 followed by vitrification (Kitazato). PGT-A was processed by comparative genomic hybridization (aCGH) on the Agilent platform. The transfer of thawed embryos of Group A (with PGT-A) and Group B (without PGT-A) was conducted into the uterine cavity under ultrasound control.

Main results and the role of chance
A total of 2318 blastocysts have been analyzed for the study. The proportion of euploid/aneuploid embryos in females under 35 years was 60.5/39.5%, respectively. In the category of over 35, this ratio was inverse - 41.9/58.1%.
The results of the study haven't revealed statistical differences in age category under 35 years in CPR between Groups A, B, and C and amounted to 58.9% (227/385), 58.7% (637/1084), and 58.9% (482/936), respectively. However, in the category of women over 35 CPR was significantly higher (p &lt; 0.001) in Group A - 53.2% (134/252) compared with Groups B - 40.9% (167/408) and C - 39.0% (185/474).
Early pregnancy losses in patients under 35 in Group B were remarkably higher compared to Group A and composed to 12.2% (16/227) vs 7.1% (78/637), respectively (p &lt; 0.05). A similar trend was traced in these groups in females over 35 -14.4% (24/167) vs 8.9% (12/134).
The percentage of LBR in women over 35 years was significantly higher (p &lt; 0.001) in Group A - 48.4%, compared to Groups B and C (35 and 34.2%). We did not find a notable difference between the two groups in women aged under 35. Relationships between variables were assessed by Student’s T-test.

Limitations, reasons for caution
The current study is limited due to the results of mosaic embryo transfers were excluded.

Wider implications of the findings
Although using PGT-A is growing each year, a significant increase in the rate of CPR and LBR was noted only in women over 35 years of age. However, concerning safety, in patients undergoing PGT-A, the risk of having a child with chromosomal diseases is significantly reduced.

Trial registration number
NA