Effect of Insemination Methods on Pregnancy Outcomes of Day 6 Blastocyst Transfer in Frozen Cycles / 中山大学学报(医学科学版)

ABSTRACT

ObjectiveTo compare the effects of two different insemination methods， conventional in vitro fertilization （IVF） and intracytoplasmic sperm injection （ICSI）， on pregnancy outcomes in patients with frozen-thawed D6（day 6） blastocyst transfer. MethodsA retrospective cohort study was conducted to analyze the clinical data of patients with thawed D6 blastocyst transfer between January 2018 and April 2020 at the Fertility Center of the Third Hospital of Sun Yat-sen University， divided into conventional IVF group （446 cycles ） and ICSI fertilization group （200 cycles） according to the fertilization method. Patients were divided into those with a history of D5（day 5） blastocyst transfer and those without. The patients’ general characteristics， blastocyst quality， and pregnancy outcomes of the two groups were compared. ResultsBMI， years of infertility， and basal FSH were not statistically significant in the IVF and ICSI groups （P > 0.05）. Regardless of the history of D5 transfer， patients in the ICSI group were younger than those in the IVF group （P < 0.001）， the proportion of primary infertility was significantly higher in the ICSI group （P < 0.001）， and the number of oocytes obtained and the number of normally fertilized oocytes in the ICSI group were higher than those in the conventional IVF fertilization group （P < 0.001）. The proportion of stage V and Ⅵ blastocysts was significantly higher in the conventional IVF group than in the ICSI group （21.6 % vs. 3.14 %， P < 0.001）. High-quality blastocysts with an ICM score of A were significantly higher in the ICSI group than in the IVF group （23.8 % vs. 14.3 %， P = 0.01）. The HCG-positive and clinical pregnancy rates were significantly higher in the ICSI group than in the IVF group （65.5 % vs. 48.4 %， P < 0.001； 56 % vs. 41.3 %， P = 0.001）， and embryo implantation and live birth rates were also higher in the ICSI group than in the conventional IVF group （43.8 % vs. 30.9 %， P < 0.001； 43.0 % vs. 31.8 %， P = 0.006）. After correcting for age and number of oocytes obtained between the two groups， the clinical pregnancy rate was still significantly higher in the ICSI group than in the conventional IVF group （OR： 1.590， 95 % CI： 1.030， 2.455， P = 0.036）. Infant birth weight was lower in the ICSI group than in the IVF group （P = 0.016）， and the differences in preterm birth rate， sex ratio， and mode of delivery were not statistically significant between the two groups. ConclusionsClinical pregnancy and live birth rates after thawing and transfer of D6 blastocysts fertilized by ICSI are higher than those of D6 blastocysts fertilized by conventional IVF， which may be related to the different factors contributing to the slow development of blastocysts in patients who received different fertilization methods. The relatively good pregnancy outcome after the transfer of thawed D6 blastocysts fertilized by ICSI may compensate to some extent for the difference in pregnancy outcome due to the relatively slow blastocyst development and a relatively higher proportion of D6 blastocysts after ICSI fertilization in male infertility patients.