Analysis of key factors influencing clinical pregnancy outcomes in high-quality single blastocyst frozen-thawed transfer cycles

Summary Currently, the research on the key factors which affect clinical and non-clinical pregnancy in high-quality single blastocyst transfer cycles remains relatively limited. This is particularly true for FET cycles, where the relationship between the transfer of high-quality single blastocysts and pregnancy outcomes has not been fully explored. This study aimed to identify key factors influencing clinical pregnancy outcomes in high-quality single blastocyst frozen-thawed transfer cycles to optimize assisted reproductive technology (ART). Patients under 38 years old who underwent high-quality single blastocyst frozen-thawed embryo transfer were included. Based on clinical pregnancy outcomes, they were divided into clinical pregnancy (Group A) and non-clinical pregnancy (Group B) groups. Key influencing factors were analyzed to guide the selection of blastocysts with the highest pregnancy potential.The result showed that Group B showed significantly higher age and infertility duration, but lower AMH levels, antral follicle count, and endometrial thickness on the day of transfer compared to Group A ( P < 0.01). Infertility type also differed significantly ( P < 0.01). Blastocyst grading differed between groups ( P < 0.01), while E2, LH, P levels, embryo age, and D3 cleavage-stage cell count showed no significant differences ( P > 0.05). Multivariate analysis revealed that infertility type, age, infertility duration, and endometrial thickness significantly impacted clinical pregnancy outcomes ( P < 0.05), while AMH, antral follicle count, and blastocyst grading had no significant effect. All in all, clinical pregnancy outcomes are significantly influenced by age, infertility type, infertility duration, and endometrial thickness. Early treatment, optimized endometrial conditions, and selecting high-quality blastocysts are recommended to improve pregnancy rates.