A Study Of Non-Invasive Methods For Assessing Embryo Quality

Purpose:We investigated if the time-lapse imaging(TLI)classification model combine with the expression of soluble human leukocyte antigen G(sHLA-G)in embryos’ day3(D3)medium can be a valuable strategy to identify those embryos with the best implantation potential.The purpose of this study is to find an effective non-invasive detection method for assessing the quality of embryos.Methods:This is a retrospective study which performed on a group of 146 infertile patients who had undertaken FET(Frozen-thawed embryo transfer)at Reproductive Medicine center of Northern Jiangsu People’s Hospital from May 2017 to September 2018.According to pregnancy outcomes,cycles were divided into two groups namely pregnancy group and non-pregnant group.We used a retrospective analysis to compare general clinical data.We examined sHLA-G levels in the embryo culture medium(ECM)(in vitro culture day 3)by an enzyme-linked immunosorbent assay(ELISA).And we analyzed the TLI morphokinetic parameters during embryonic development.The embryos were divided into sHLA-G positive group and negative group according to the result of sHLA-G measurement,to compare the average sHLA-G levels and implantation rate between the two groups.Furthermore,we divided the embryos into the implantation group and the non-implantation group according to the pregnancy outcome of the embryos in order to compare the difference of TLI morphokinetic parameters between the groups.We used quartile and multivariate logistic regression analysis to find parameters related to embryo implantation potential and then developed a TLI classification model which classified the embryos in five groups(A,B,C,D,E).We finally figured out the relationship between sHLA-G expression in D3 ECM with the TLI classification of embryos and embryo pregnancy outcome.Results:(1)In our study,there was no significant difference between pregnancy group(n=58)and non-pregnancy group(n=107)in terms of the following clinical characteristics:age,BMI(body mass index),duration of infertility,types of infertility,fertilization method,basal serum FSH(follicle stimulating hormone),LH(luteinizing hormone),E2(estradiol)levels or endometrial thickness,days for gonadotropin use and the total dose for gonadotrophins use,the number of transferred embryos.The numbers of antral follicle,retrieved oocytes and MII oocytes were significantly more in pregnancy group than non-pregnancy group(P<0.05).(2)The average sHLA-G levels and implantation rate of sHLA-G positive group greater than sHLA-G negative group and the difference was statistically significant(P<0.05).(3)We compared the morphokinetic parameters(t2,t3,t4,t5,t6,t7,t8,cc2,s2,cc3,s3)between implantation embryos and non-implantation embryos revealed that t3,cc2,s3 were longer in implantation group than in non-implantation group and t5,s2,cc3 were shorter in implantation group than in non-implantation group(P<0.05)).No statistically significant between-group differences were found for any of the other variables assessed.(4)The results of multivariate Logistic regression analysis showed that TLI parameters-t5 and s3 and the content of sHLA-G are independent risk factors influencing embryo implantation.(5)The implantation rate decreases with the decline of TLI classification from A to E.The TLI classification model presented here was capable of assessing the implantation potential of the embryos with an AUC(area under curve)of 0.844.(6)We compared the implantation rate and sHLA-G positive embryo rate of the hierarchical classification model and found a largely downward trend.The sHLA-G expression in D3 ECM combined with the TLI classification of embryos can estimate the implantation potential of the embryos with an AUC of 0.876.Conclusions:(1)There was a positive correlation between the sHLA-G expression in the embryo culture medium and the clinical pregnancy rate,we found sHLA-G levels in D3 medium were independent risk factors for pregnancy outcome.(2)The TLI morphokinetic algorithm model based on parameter t5,s3 and irregular division pattern was a good indicator of embryonic developmental.(3)The expression of sHLA-G in D3 ECM of embryos combined with the TLI classification model is a useful non-invasive tool to identify embryos with the highest potential for implantation and pregnancy.