Research Question. What is the incidence of de novo chromosome abnormalities (>4 Mb), and are they related to embryo parameters in preimplantation genetic testing for chromosome structural rearrangement (PGT-SR) cycles and preimplantation genetic testing for aneuploidy (PGT-A) cycles? Design. In total, 456 PGT cycles, including 283 PGT-SR cycles and 173 PGT-A cycles, were assessed through comprehensive chromosome screening (CCS) from January 2017 to June 2020 at the Department of Reproductive Medicine of the Third Affiliated Hospital of Zhengzhou University. Trophectoderm (TE) biopsies were sequenced using next-generation sequencing (NGS). The incidence of de novo chromosome abnormalities was calculated, and the relationships between de novo chromosome abnormality rates and maternal age, number of oocytes retrieved, and parameters of cleavage-stage embryos and blastocyst-stage embryos were investigated. Results. The incidence of de novo chromosome abnormalities was 28.0% (318/1,135) in the PGT-SR cycles and 36.3% (214/590) in the PGT-A cycles, which increased with maternal age in both PGT-SR cycles ( P  = 0.018) and PGT-A cycles ( P  < 0.001). The incidence of de novo chromosome abnormalities was related to TE grade ( P  < 0.001), internal cell mass grade ( P  = 0.002), and development speed (day 5 vs. day 7: P  < 0.001) of blastocyst-stage embryos. The incidence of de novo chromosomal abnormalities was irrelevant to the number of oocytes retrieved and the parameters of the embryo at the cleavage stage. Conclusion. Blastocysts with higher morphology scores and faster progression had a lower incidence of de novo chromosome abnormalities, especially complex chromosome abnormalities. De novo chromosome abnormalities may negatively affect the morphological grading of blastocysts. Our findings will provide valuable information to the fertility doctor for embryo selection in non-PGT cycles.

ObjectiveThis study aimed to determine whether controlled ovarian hyperstimulation (COH) parameters influence the incidence of de novo chromosomal abnormalities (&gt; 4 Mb) in blastocysts and, thus, clinical pregnancy outcomes in preimplantation genetic testing (PGT).MethodsCouples who underwent preimplantation genetic testing for structural chromosome rearrangements (PGT-SR) and monogenic disorders (PGT-M) were included in this study. The relationships of maternal age, paternal age, stimulation protocol, exogenous gonadotropin dosage, duration of stimulation, number of oocytes retrieved and estradiol (E2) levels on human chorionic gonadotropin (hCG) trigger day with the incidence of de novo chromosomal abnormalities were assessed. Blastocysts were biopsied, and nuclear DNA was sequenced using next-generation sequencing (NGS). Clinical pregnancy outcomes after single euploid blastocyst transfers under different COH parameters were assessed. ResultsA total of 1,710 and 190 blastocysts were biopsied for PGT-SR and PGT-M, respectively. The rate of de novo chromosomal abnormalities was found to increase with maternal age (p&lt; 0.001) and paternal age (p = 0.019) in the PGT-SR group. No significant differences in the incidence of de novo chromosomal abnormalities were seen for different maternal or paternal age groups between the PGT-SR and PGT-M groups (p &gt; 0.05). Stratification analysis by gonadotropin dosage, stimulation protocol, duration of stimulation, number of retrieved oocytes and E2 levels on hCG trigger day revealed that de novo chromosomal abnormalities and clinical pregnancy outcomes were not correlated with COH parameters after adjusting for various confounding factors.ConclusionThe rate of de novo chromosomal abnormalities was found to increase with maternal or paternal age. COH parameters were found to not influence the incidence of de novo chromosomal abnormalities or clinical pregnancy outcomes.