Received June 24, 2020
Accepted July 24, 2020

Objective:To assess the relationship between human blastocyst chromosomal ploidy established by niPGT-A and increasing age. Methods:Multicenter study carried out by ten assisted reproduction centers after their embryologists acquired training and validated their results with the previous use of niPGT-A. 94 couples were included in this study. After ICSI, the embryos were cultured until blastocyst. On day 3, we re-evaluated cleavage embryos to complete cumulus cells removal. The embryos were then cultured in individual well, with 20µl of medium under oil until they reached blastocyst stage. The blastocysts were vitrified and stored in liquid nitrogen. After that, the spent blastocyst culture medium was transferred to a PCR tube and sent for analysis in the genetic laboratory, where it was stored at -80°C until sequencing. A total of 243 samples of spent blastocyst culture medium were collected on the 5th/6th day. Cell-free DNA secreted on culture medium was amplified using NICS Sample Preparation Kit(Yikon Genomics)/MALBAC technology. The DNA was measured using a Qubit2.0 fluorometer and subjected to NGS. The data were analyzed using the ChromGo® software(Yikon Genomics). Results:The mean age of the patients was 38±4.08y. The euploid:36.4%(80/220), aneuploidy:31.3%(69/220), and mosaicism:32.3%(71/220;≥60%aneuploidy) of blastocysts. Mosaic values ranged from 29.8%-33.8% in different age groups. Individually, the most frequent chromosomal abnormality was XXY(18 cases), followed by chromosome 21(trisomy/monosomy-8cases). The niPGT-A data showed a ≥60% incidence of aneuploid cells in all cases of chromosomal mosaicism(n=71). Conclusion:A high degree of mosaicism with aneuploidy cells was detected, and some hypotheses were suggested for this data(niPGT-a sensitivity in detecting the self-correction of chromosomal abnormalities phenomenon). However, it did not vary remarkably with age. On the other hand, euploidy levels had a negative correlation with age and aneuploidy levels had a positive relationship. This is the first report in the literature to relate chromosomal ploidy in blastocysts using niPGT-A and increasing patient age.