The Influence of Single Nucleotide Polymorphism Microarray-Based Molecular Karyotype on Preimplantation Embryonic Development Potential

Improving the clinical outcomes by extended culture of day 3 embryos with low blastomere number to blastocyst stage following frozen-thawed embryo transfer

Purpose

This study aimed to investigate whether the extended culture of day 3 (D3) embryos with low blastomere number to blastocyst following frozen–thawed embryo transfer improved the clinical outcomes.

Methods

This was a retrospective study of clinical data of women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles in the Tangdu Hospital. The patients were divided into groups with 4–5, 6, 7–9 and > 9 cells based on the blastomere number of D3 embryos. The clinical outcomes were compared.

Results

In fresh transfer cycles, the implantation and clinical pregnancy rates significantly decreased, while the abortion rate significantly increased in the groups with 4–5 and 6 cells compared with those with 7–9 and > 9 cells. In frozen–thawed transfer cycles, the clinical pregnancy and implantation rates for a single blastocyst transfer cycle showed no significant differences in the groups with 4–5 and 6 cells compared with those with 7–9 and > 9 cells. However, the abortion rate was significantly higher in the group with 4–5 cells than in that with 7–9 and > 9 cells. In the double blastocyst transfer cycle, the clinical pregnancy rate showed no significant differences among the groups with 4–5, 6, and 7–9 cells.

Conclusion

The implantation and clinical pregnancy rates of D3 embryos with 6 cells significantly decreased; these embryos were not considered as high-quality embryos. Extended culture of D3 embryos with ≤ 6 blastomeres to blastocysts, particularly 6-cell embryos, resulted in a similar clinical pregnancy rate as that of blastocysts derived from D3 embryos with ≥ 7 blastomeres.

Number of blastocysts biopsied as a predictive indicator to obtain at least one normal/balanced embryo following preimplantation genetic diagnosis with single nucleotide polymorphism microarray in translocation cases

Purpose

The aim of this study is to investigate the minimum number of blastocysts for biopsy to increase the likelihood of obtaining at least one normal/balanced embryo in preimplantation genetic diagnosis (PGD) for translocation carriers.

Methods

This blinded retrospective study included 55 PGD cycles for Robertsonian translocation (RT) and 181 cycles for reciprocal translocation (rcp) to indicate when only one of the couples carried a translocation. Single-nucleotide polymorphism microarray after trophectoderm biopsy was performed.

Results

Reliable results were obtained for 355/379 (93.7 %) biopsied blastocysts in RT group and 986/1053 (93.6 %) in rcp group. Mean numbers of biopsied embryos per patient, normal/balanced embryos per patient, and mean normal/balanced embryo rate per patient were 7.4, 3.1, and 40.7 % in RT group and 8.0, 2.1, and 27.3 %, respectively, in rcp group. In a regression model, three factors significantly affected the number of genetically transferrable embryos: number of biopsied embryos (P = 0.001), basal FSH level (P = 0.040), and maternal age (P = 0.027). ROC analysis with a cutoff of 1.5 was calculated for the number of biopsied embryos required to obtain at least one normal/balanced embryo for RT carriers. For rcp carriers, the cutoff was 3.5. The clinical pregnancy rate per embryo transfer was 44.2 and 42.6 % in RT and rcp groups (P = 0.836).

Conclusions

The minimum numbers of blastocysts to obtain at least one normal/balanced embryo for RT and rcp were 2 and 4 under the conditions of female age < 37 years with a basal FSH level < 11.4 IU/L.

Comparison of differences in development potentials between frozen-thawed D5 and D6 blastocysts and their relationship with pregnancy outcomes

PURPOSE

Whether there are differences in the pregnancy outcomes of blastocysts cryopreserved during different developmental stages remains under debate because the results among studies are inconsistent. We analyzed blastocyst quality and pregnancy outcomes by considering blastocyst euploidy and investigated the differences in the development potential between blastocysts of different developmental stages (frozen-thawed day 5 [D5] and day 6 [D6] cycles) and their relationship with clinical pregnancy outcomes.

METHODS

In total, 1374 D5 and 255 D6 frozen-thawed blastocyst transfer cycles were retrospectively analyzed. Additionally, the chromosome euploidy and clinical pregnancy rates of 237 blastocysts from 50 pre-implantation genetic diagnosis (PGS) cycles were statistically analyzed. The corresponding euploidy rate and pregnancy outcomes of the D5 and D6 blastocyst transfers were also compared.

RESULTS

The clinical pregnancy rate (47.2 vs 40.0 %; P = 0.04) and implantation rate (34.2 vs 28.8 %; P = 0.03) of the D5 blastocysts were higher than were those of the D6 blastocysts. However, the clinical pregnancy rate (52.4 vs 52.6 %; P = 0.97) and implantation rate (38.9 vs 35.6 %; P = 0.39) of the high-quality D5 blastocysts did not significantly differ from those of the high-quality D6 blastocysts. Analysis of blastocyst euploidy in 237 blastocysts examined in 50 PGS cycles showed that the euploidy rates of the D5 and D6 blastocysts were both 48.1 % (P = 0.99). The clinical pregnancy rate of the D5 blastocysts (48.5 vs 17.6 %; P = 0.03) was higher than that of the D6 blastocysts. The euploidy rates (55.2 vs 55.3 %; P = 0.99) and clinical pregnancy rates (60.0 vs 42.9 %; P = 0.77) of the high-quality D5 and D6 blastocysts did not differ. The euploidy rate (55.3 vs 41.5 %, P = 0.03) and clinical pregnancy rate (54.5 vs 25.0 %, P = 0.03) of the high-quality blastocysts were higher than were those of the poor-quality blastocysts.

CONCLUSIONS

The euploidy rates between the D5 and D6 blastocysts did not differ. High-quality D6 blastocysts in frozen-thawed cycles had similar developmental potential and pregnancy outcomes compared to those of high-quality D5 blastocysts. The quality of the blastocysts was an important factor that affected the pregnancy outcomes of the frozen-thawed cycles.