Effect Of Blastocyst Morphological Score On Pregnancy And Neonatal Outcome Of Single Blastocyst Transfer

With the development of human assisted reproductive technology（ART）,its effectiveness and safety have received extensive attention.In the past,two or more embryos were usually transferred in order to increase the clinical pregnancy rate and live birth rate.However,this also increases the risk of ovarian hyperstimulation syndrome（OHSS）and multiple pregnancy-related obstetric complications in infertility patients.In addition to the risk of maternal and infant safety,multiple pregnancy also brings great pressure to the society and family economy.Studies have also shown that the incidence of depression and anxiety increases,the quality of life decreases,and marital dissatisfaction increases after multiple pregnancy^[1].At present,it is widely recognized that multiple pregnancies are the greatest risk to the health of mothers and perinatal infants treated with ART.In order to reduce the risk of multiple pregnancies,reproductive medicine experts have been looking for an effective solution.It is accepted that multiple pregnancies after IVF-ET（in vitro fertilization and embryo transfer）can be avoided by reducing the number of embryos transferred.As a simple and effective method to identify the quality of blastocysts,most IVF laboratories around the world still refer to evaluate the morphological parameters of blastocysts under the optical microscope to select embryos for transfer.Therefore,the purpose of this study is to systematically evaluate the independent effect of existing blastocyst morphological indicators on the prognosis of blastocyst transplantation,in order to provide a basis for finding the best choice of blastocyst transfer.ObjectivesTo investigate the independent effect of blastocyst morphological score on pregnancy and neonatal outcome of single blastocyst transfer,so as to provide a basis for evaluation of the safety and effectiveness of blastocyst transfer.Materials and Methods1.Study population:This study retrospectively analyzed the clinical data of women who received in vitro fertilization（IVF）or intracytoplasmic sperm injection（ICSI）fresh and FET cycle’s single blastocyst transfer from August 1,2015 to December 25,2019 in the Reproductive Center of the Third Affiliated Hospital of Zhengzhou University.2.Inclusion criteria:（1）patients receiving IVF/ICSI therapy;（2）single blastocyst transfer cycle;（3）first fresh or FET（frozen-thawed embryo transfer）embryo transfer cycle.Exclusion criteria:（1）patients receiving Preimplantation Genetic Testing（PGT）;（2）pregnancy outcome was stillborn or identical twins;（3）combined with abnormal uterine cavity,hydrosalpinx,ovarian deficiency and other organic diseases;（4）patients with recurrent spontaneous abortion;（5）using donated oocytes;（6）cycles of important data loss.3.Grouping:the study cohort was divided into two groups:live birth group and non-live birth group.In the live birth group,blastocyst morphology scores（blastocyst expansion stage,inner cell mass（ICM）,trophectoderm（trophectoderm,TE））were further grouped.4.Statistical methods:All statistical analyses were performed using SPSS 21.0.Continuous variables were expressed as mean±standard deviation（mean±SD）,and T-test or Mann-Whitney U test was used for comparison between groups.Categorical variables were expressed by rate（%）,and Chi-square test or Fisher exact test was used for comparison between groups.Binary Logistic regression analysis was used to test the correlation between blastocyst morphological parameters and neonatal outcome.The statistical significance was set at P<0.05.ResultsAccording to the above inclusion and exclusion criteria,a total of 1627 fresh cycles and 3052 FET cycles were included in the study,of which 812 fresh cycles and1332 freezing cycles were obtained singleton live birth,and the single birth rate was49.9%and 43.6%,respectively.1.The effect of blastocyst morphology score on pregnancy outcome.Binary Logistic regression analysis was used to assess the correlation between blastocyst morphology score and live birth.There was no significant correlation between them after adjusting the confounding factors,but ICM grade was an independent influencing factor of live birth（fresh cycle P<0.001;FET cycle P=0.008）.TE grading was an independent factor affecting to the live birth in the FET cycle（P<0.001）.2.The effect of blastocyst morphology score on neonatal outcome.In the live birth group,the binary Logistic regression analysis was conducted with the neonatal outcome as the dependent variable.It was no found correlation between blastocyst expansion stage,ICM grade,TE grade and LGA,SGA,FM,LBW and PTB after adjusting the confounding factors in the fresh cycle or frozen cycle.In the fresh cycle,ICM grade（P<0.001）and TE grade（P<0.001）were independent influencing factors of SSR.The sex ratio of blastocysts with ICM grade"B"was significantly higher than grade A（AOR=2.17 95%Cl（1.51,2.94）P<0.001）.The sex ratio of blastocysts with TE grade"B"and"C"was lower than"A",and the corresponding AOR（95%Cl）was 0.56（0.38,0.78）and 0.35（0.22,0.55）respectively.In the FET cycles,the sex ratio of blastocysts with TE grade"B"and"C"was lower than"A"grade（P=0.001）after adjusting the confounding factors.The corresponding AOR（95%Cl）are 0.78（0.54,1.10）and 0.53（0.36,0.78）,respectively.However,there was no significant correlation between ICM grade and SSR（P=0.059）.Conclusions1.In the IVF/ICSI single blastocyst transfer cycle,the live birth rate decreased with the decrease of TE score and ICM score.ICM grading is an independent influencing factor of live birth,and TE grading is only independently related to live birth during the freezing cycle,while blastocyst expansion stage did not affect the outcome of live birth.2.For live births after single blastocyst transfer,even if the morphological score is low,it will not increase the risk of adverse neonatal outcomes,including LGA,SGA,FW,LBW,PTB;3.Sex ratio was positively correlated with TE grading and negatively correlated with ICM grading;TE grading was an independent influencing factor of fresh cycle and freezing cycle SSR,and ICM grading was an independent influencing factor of fresh cycle SSR.