| Objective:By comprehensively analyzing some related factors that might influence the outcome of the natural cycle frozen-thawed embryo transfer(FET),the relationship between these factors and the clinical pregnancy rate,embryo implantation rate and abortion rate of FET was discussed,so as to provide basis for improving the outcome of FET pregnancy in clinical practice and also to pave the way for further research.Methods:Clinical data and laboratory data of 1,906 frozen-thawed embryo transfer cycles conducted in the reproductive medicine research center of the first affiliated hospital of guangxi medical university from November 2016 to October 2018 were collected as research objects,The relationship between the age,infertility years,body mass index(BMI),intrauterine membrane thickness on the day of transplantation,the mode of fertilization,the number of transplanted embryos,the number of transplanted well-formedembryosandembryonicdevelopmentdays(Day3,Day5,Day6)and the clinical pregnancy rate,embryo implantation rate and abortion rate of these patients,as well as the influence on the outcome of FET were analyzed retrospectively.The specific groups are as follows:1.According to the age,the patients were divided into three groups:?30 years old group,31-34 years old group and?35 years old group;2.According to the infertility years,the patients were divided into three groups:<5 years group,5-10 years group and>10 years group;3.According to body mass index,the patients were divided into three groups:<18.5 kg/m~2 group,18.5-27 kg/m~2 group,and>27kg/m~2 group;4.According to Intrauterine thickness on days of transplantation,the patients were divided into:<7mm group,7-12mm group,and>12mm group;5.According to fertilization methods,the patients were divided into:conventional IVF group and ICSI group;6.According to the number of transferred embryos,the patients were divided into:1 embryo group,2 embryos group and 3 embryos group;7.According to the number of transferred well-formed embryos,the patients were divided into:0 well-formed embryo group,1 well-formed embryo group,2 well-formed embryos group;8.According to the embryo development days,the patients were divided into:Day3 group(cleavage stage group),Day5 group(blastocyst stage),Day6 group(blastocyst stage).Finally,binary Logistic regression was used to analyze these factors that may affect the outcome of FET pregnancy in natural cycle,and the corresponding conclusions were drawn.Results:In this study,a total of 1,906 Frozen-thawed embryo transfer cycles were performed:the average age of the patients was33.70±4.53 years old;A total of 3,680 embryos were thawed and3,582 survived,so the recovery rate of thawed embryos in this study was 97.34%;The thawed embryos were all transplanted on the same day,the average number of frozen embryos transplanted per cycle was 1.88±0.44;the number of embryos successfully implanted was932,so the embryo implantation rate in this study was 26.02%;A total of 757 clinical pregnancy cycles were obtained,so the clinical pregnancy rate was 39.72%;Abortion has 117 cycles,the abortion rate was 15.46%.The chi-square test results of each group of data are as follows:1.Age factor:The clinical pregnancy rate and embryo implantation rate of frozen-thawed embryo transfer in patients aged?35 years old group were significantly both lower than those in the other two groups(P<0.05).The abortion rate in the?35 years old group was significantly higher than the other two groups(P<0.05).2.2.Infertility years:among the three groups of<5 years group,5 to 10 years,>10 years were compared,the differences of the frozen-thawed embryos clinical pregnancy rate,implantation rate and abortion rate were not statistically significant(P>0.05).3.Body mass index:There were no statistically significant differences in clinical pregnancy rate,embryo implantation rate and abortion rate among the<18.5kg/m~2 group,the 18.5-27 kg/m~2 group and the>27 kg/m~2 group(P>0.05).4.Intrauterinemembranethicknessonthedayof transplantation:embryo implantation rate and clinical pregnancy rate in the<7mm group were both lower than those in the other two groups,but the difference among the three groups was not statistically significant(P>0.05).There was no significant difference in abortion rate among the three groups(P>0.05).5.Fertilization method:there were no statistically significant differences in frozen-thawed clinical pregnancy rate,embryo implantation rate and abortion rate between IVF group and ICSI group(P>0.05).6.Number of transferred embryos:Comparing ET 1 embryo group,ET 2 embryos group and ET 3 embryos group,the differences of clinical pregnancy rate,implantation rate and abortion rate of frozen-thawed embryos were statistically significant(P<0.05)7.Number of the transferred well-formed embryos:ET 0 well-formed embryo,ET 1 well-formed embryo,ET 2 well-formed embryos is compared among the three groups,the frozen-thawed embryos clinical pregnancy rate and implantation rate were increased in turn,and the differences were statistically significant(P<0.05).The abortion rate of ET 0 well-formed embryo,ET 1well-formed embryo,ET 2 well-formed embryos decreased successively,and the difference was statistically significant(P<0.05).8.Embryonic development days:The clinical pregnancy rate and embryo implantation rate of Day3 group were significantly both lower than those of Day5 group(blastocyst stage)and Day6 group(blastocyst stage),and the differences were statistically significant(P<0.05).The clinical pregnancy rate and embryo implantation rate of Day5 were significantly higher than those of Day6 group(P<0.05).In the abortion rate,there was no significant difference among the three groups(P>0.05)At last,binary logistic regression analysis was carried out to analyze the relevant factors that may affect the pregnancy outcome of FET.The results showed that the age,the number of well-formed embryos and embryonic development days were the main factors affecting the pregnancy outcome of FET in the natural cycle(P<0.05);there was no significant correlation between the infertility years,body mass index,intrauterine thickness on the day of transplantation,fertilization mode,the number of embryos transplanted and clinical pregnancy rate of the natural cycle FET(P>0.05).Conclusion:1.Under the condition of vitrification freezing technology,the age of the patients,the number of well-formed embryos and the days of embryonic development are the main factors affecting the outcome of the natural cycle FET pregnancy.2.Infertility years,body mass index,intrauterine thickness on the day of transplantation,mode of fertilizationand the number of transplanted embryos were not significantly correlated with the natural cycle FET pregnancy outcomes.3.In the natural cycle,the clinical pregnancy rate and embryo implantation rate of frozen-thawed blastocyst transplantation were both better than those of frozen-thawed embryo transplantation in the cleavage period,while Day5 frozen-thawed blastocyst transplantation was better than Day6 frozen-thawed blastocyst transplantation. |
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