Abstract: Objective To analyze the statusofserologicprenatal screening and prenatal diagnosis duringthe second trimester pregnancy in Anhui Maternity and Child Health Hospital from 2016 to 2017,compare the efficiency of double and triple screening,and evaluate the significance of uE3 （estratriol）.Methods A total of 28,900 pregnant women who agreed to make prenatal screening were screened.The concentrations of AFP,Free β-hCG and uE3 were determined by time-resolved fluorescence. Risk calculation was performed using Lifecycle risk assessment software. The efficiency of screening for double test （AFP,Free β-hCG） and tripletest （AFP,Free β-hCG,uE3）,The chromosome condition disgnosed by amnioticfluid puncture and the pregnancy outcome were followed up.Results Among the 28,900 pregnant women,when the cut-off value was 1/270,the detection rate of the 21-trisomy was the same by double and triple screening,both of which were 76.92%,but the false positive rate of triple screening was greatly reduced,only 4.27%,the false positive rate of double screening is 6.23%,with statistically significant （P<0.05）.Conclusion For the screening of Down's syndrome,the screening efficiency of triple serum screening is better than double screening during the second trimester pregnancy.

Key words: Down's syndromeprenatal, Prenatal screening, Screening, efficiency Prenatal diagnosis