目的探讨妊娠中期妇女唐氏筛查对于严重先天性缺陷儿宫内诊断的临床价值以及不同高风险值诊断阳性率的差别。方法采用时间分辨免疫荧光法(DELFIA)对37267例妊娠中期妇女进行血清甲胎蛋白和游离β人绒毛膜促性腺激素检测,应用Multicalc软件计算出风险值。高风险孕妇经遗传咨询,知情同意,自愿选择行产前诊断。结果37267例孕妇中筛查出高风险孕妇2401例,阳性率为6.44%,其中唐氏综合征高风险孕妇2066例,789例(羊水463例,脐血326例)接受产前诊断,发现胎儿染色体异常38例,异常检出率为4.82%,其中唐氏综合征12例,18三体综合征1例。不同高风险值范围孕妇诊断阳性率差异无显著性(P>0.05)。结论产前筛查对于严重先天性缺陷儿的宫内诊断具有重要的临床价值,高风险是指导产前诊断的确切指征。 Objective To investigate the clinical value of Down’s screening in mid-pregnancy women for intrauterine diagnosis of severe congenital defects and the diagnostic positive rates of different high-risk patients. Methods Serum alpha-fetoprotein and free beta human chorionic gonadotrophin were detected in 37,267 pregnant women with the use of time-resolved immunofluorescence assay (DELFIA). The risk values ​​were calculated using Multicalc software. High risk pregnant women through genetic counseling, informed consent, voluntary choice of prenatal diagnosis. Results Among 37267 pregnant women, 2401 pregnant women were screened out, with a positive rate of 6.44%. Among them, 2066 were pregnant women with high risk of Down’s syndrome, 789 (463 cases of amniotic fluid and 326 cases of umbilical cord blood) were diagnosed prenatally. Chromosome abnormalities in 38 cases, the detection rate was 4.82%, of which 12 cases of Down Syndrome, 18 cases of trisomy syndrome in 1 case. There was no significant difference in the positive rate of pregnant women in different high risk range (P> 0.05). Conclusion Prenatal screening has important clinical value for intrauterine diagnosis of children with severe congenital defects. High risk is the exact indication of prenatal diagnosis.