Objective:To explore the influencing factors of clinical pregnancy rate after single cleavage embryo transfer.Methods:A total of 2 764 patients who underwent single cleavage embryo transfer in the Reproductive Medicine Center of Henan Provincial People's Hospital from January 2017 to October 2021 were included in a retrospective cohort study, The clinical data and cycle outcomes were analyzed by using univariate and multivariate logistic regression to explore the independent influencing factors of clinical pregnancy.Results:Multivariate logistic regression analysis showed that age, ovulation stimulation protocol, antral follicle number, blastomere number, fragment ratio, endometrial thickness, elective single embryo transfer were independent influencing factors of clinical pregnancy rate (all P<0.05). The effect of blastomere number on clinical pregnancy rate ( OR=2.92, 95% CI: 1.58-5.39) was stronger than that of fragment ratio ( OR=0.73, 95% CI: 0.55-0.98). The results of further stratified analysis showed that when the number of embryo cells was 8, the clinical pregnancy rate of patients less than 35 years old was significantly increased regardless of whether the embryo fragment ratio was more than 10% or not ( OR=4.78, 95% CI: 3.06-7.47; OR=3.53, 95% CI: 1.85-6.76), while in patients ≥35 years old, when the fragment ratio of transferred embryos was less than 10%, the clinical pregnancy rate of 8-cell embryos was significantly higher than that of 4-6-cell embryos ( OR=3.58, 95% CI: 1.64-7.84). Conclusion:The blastomere number and fragment ratio are the main influencing factors of the clinical pregnancy rate of single cleavage embryo transfer in young patients and the former has a stronger correlation with the clinical pregnancy rate. The decrease of blastomere number of transferred embryos is related to the decrease of clinical pregnancy rate. Cleavage embryos with 8 cells and fragment ratio less than 10% should be preferred for transfer.

Objective:To explore the influencing factors of clinical pregnancy rate after single cleavage embryo transfer.Methods:A total of 2 764 patients who underwent single cleavage embryo transfer in the Reproductive Medicine Center of Henan Provincial People's Hospital from January 2017 to October 2021 were included in a retrospective cohort study, The clinical data and cycle outcomes were analyzed by using univariate and multivariate logistic regression to explore the independent influencing factors of clinical pregnancy.Results:Multivariate logistic regression analysis showed that age, ovulation stimulation protocol, antral follicle number, blastomere number, fragment ratio, endometrial thickness, elective single embryo transfer were independent influencing factors of clinical pregnancy rate (all P<0.05). The effect of blastomere number on clinical pregnancy rate ( OR=2.92, 95% CI: 1.58-5.39) was stronger than that of fragment ratio ( OR=0.73, 95% CI: 0.55-0.98). The results of further stratified analysis showed that when the number of embryo cells was 8, the clinical pregnancy rate of patients less than 35 years old was significantly increased regardless of whether the embryo fragment ratio was more than 10% or not ( OR=4.78, 95% CI: 3.06-7.47; OR=3.53, 95% CI: 1.85-6.76), while in patients ≥35 years old, when the fragment ratio of transferred embryos was less than 10%, the clinical pregnancy rate of 8-cell embryos was significantly higher than that of 4-6-cell embryos ( OR=3.58, 95% CI: 1.64-7.84). Conclusion:The blastomere number and fragment ratio are the main influencing factors of the clinical pregnancy rate of single cleavage embryo transfer in young patients and the former has a stronger correlation with the clinical pregnancy rate. The decrease of blastomere number of transferred embryos is related to the decrease of clinical pregnancy rate. Cleavage embryos with 8 cells and fragment ratio less than 10% should be preferred for transfer.