Logistic Regression Analysis Was Employed To Explore The Influencing Factors Of Non-Invasive Prenatal Testing Failure

Objective:In this study,multivariate logistic regression analysis was employed to analyze the effecting elements of non-invasive prenatal.The relationship between the failure of NIPT and maternal age,eight,BMI,cell free fetal DNA concentration,sampling gestational age,type of pregnancy（singleton/twins）,whether labor,whether treated with heparin,mode of conception（natural pregnancy/assisted reproductive）was analyzed.Methods:3410 pregnant women who received NIPT test in Dalian municipal women and children’s center from July 2019 to June 2020 were retrospectively analyzed.Group A was the first screening failure group,and group B was the first screening success group.The differences of general information between the two groups were analyzed and contrasted,and the factors with differences were channelled into the logistic regression equation to summarize the influencing factors of NIPT failure Objective to provide a theoretical basis for the standardized application of NIPT in clinical practice.SPSS 25.0 software was employed to data statistics and analysis,the measurement data was expressed as mean±standard deviation（?x±s）,the two groups of samples used independent sample t test/rank sum test;the data of classified variables was expressed as percentage（%）,the comparison of the two groups of sample rates used x²test,P<0.05,the difference was statistically significant.Results:1.3410 cases of pregnant women with NIPT,60 cases did not get the results,the first screening failure rate was 1.76%,which was tally with the results covered in the previous literary data（1.58%-6.39%）^[1-2].2.Comparison of clinical data:compare the age,weight,BMI,gestational age,cell free fetal DNA concentration,pregnancy status（singleton/twins）,whether labor,whether to use heparin treatment and the way of pregnancy between the two groups.The results showed that:there were clearly differences between the two groups in gestational age,cell free fetal DNA concentration,pregnancy status（singleton/twins）,labor and heparin treatment（P<0.05）;the sampling gestational age and cell free fetal DNA concentration in the screening failure group were lower than those in the screening success group;the proportion of twin pregnancy and heparin treatment in the screening failure group were higher than those in the screening success group;The proportion of pregnant women in the failure group was lower than that in the success group.There was no significant difference in age,weight,BMI and pregnancy mode between the two groups（P>0.05）.3.The indicators with differences between the groups were included in the logistic regression equation.The results showed that there were significant differences in the influence of sampling gestational age,cell free fetal DNA concentration and heparin treatment on the failure of NIPT detection（P<0.05）.The pregnancy status（singleton/twins）and whether or not in labor had no significant effect on the failure of NIPT detection（P>0.05）.Among them,the risk of screening failure increased with the decrease of cell free fetal DNA concentration（OR,0.599;95%confidence interval,0.513-0.700）and sampling gestational age（OR,0.931;95%confidence interval,0.845-1.026）;the risk of first screening failure of pregnant women treated with heparin was 8.771 times that of pregnant women without heparin（OR,8.771;95%confidence interval,2.708-28.409）.4.By multivariate logistic regression analysis,the regression equation of NIPT screening failure was determined as logit（P）=-9.867+0.319*sampling gestational age.The value of sampling gestational age in the logistic regression analysis model was used as the test variable to make the ROC curve,the area under the curve was 0.742,and the Youden index was 0.427,the cut-off value was 16.36 weeks;by multivariate logistic regression analysis,the final regression equation of NIPT screening failure was determined as logistic（P）=0.405-0.517*fetal free DNA concentration,and the ROC curve was made with the fetal free DNA concentration as the test variable in the logistic regression analysis model,the area under the curve was 0.755,the Youden index was0.47,and the critical value was 11.14%.5.Among the 60 patients who failed in the first screening,41 cases were due to low fetal DNA concentration,1 case was due to quality control factors,and 18 cases were in the critical area（"gray area"）of Z value.Among the 60 samples that need to be re sampled,41 samples were actually re sampled,of which 25 samples obtained NIPT results,and the total failure rate was 1.0%（35/3410）.6.Among the 3410 samples in this study,the average gestational age 17.97±1.87 and BMI 23.17±3.49 kg/m²of the first test success group,and the average gestational age16.24±2.13 and BMI 22.86±3.72 kg/m²of the first test failure group were respectively.There was significant difference in gestational age between the two groups（P<0.05）.The gestational age of failure group was significantly lower than that of success group.In this study,3226 cases of singleton pregnancy and 184 cases of twin pregnancy were included:（1）the average gestational weeks and BMI of pregnant women with successful detection for the first time in singleton pregnancy were 16.30±2.13 weeks and 23.09±3.48 kg/m²respectively.After analyzing the clinical data of failed detection in singleton group,it was found that the average gestational weeks was16.54±2.20 weeks,and the average BMI was 23.48±3.64 kg/m².In singleton pregnancy,there was clearly difference in BMI between the successful detection group and the failed detection group.The BMI of the failed detection group was higher than that of the successful detection group,but not more than 25 kg/m².（2）The average gestational age and BMI of the pregnant women with successful detection for the first time in twin pregnancy were 15.22±1.76 weeks and 23.74±3.42kg/m².After analyzing the clinical data of twin pregnancy failure,it was found that the average gestational weeks was 16.5±1.40 weeks,and the average BMI was 25.87±2.14 kg/m².In twin pregnancy,there was significant difference in BMI between the first successful detection group and the first failed detection group.The BMI of the failed detection group was significantly higher than that of the successful detection group,and greater than 25 kg/m².（3）In the first test failure of 7 twin pregnancy samples,low cell free fetal DNA ratio and Z value"gray area"were the main influencing factors,which were 57.1%（4/7）and 42.9%（3/7）,respectively.In the 4 cases with low DNA ratio,BMI>25 kg/m²,heparin was used before detection,and assisted reproductive technology was used.Among the 3 cases with Z value gray area,2 cases with BMI>25kg/m²had been treated with heparin,and they were assisted reproductive technology.Conelusions:1.Gestational age at the time of sampling,cffDNA concentration and heparin treatment were the independent factors for the failure of the first detection of NIPT.2.Based on logistic regression analysis and ROC curve,the predictive value of sampling gestational age and cffDNA concentration for the first NIPT screening failure was evaluated,and the regression equation was established.The optimal sampling gestational age was 16.36 weeks and the fetal free DNA concentration was 11.14%,which provided reference for NIPT screening.