目的探讨孕中期唐氏综合征血清学筛查、诊断在预防出生缺陷中的价值。方法应用时间分辨免疫荧光法对33 666例孕15-20w孕妇进行血清学筛查,对高风险孕妇做进一步产前诊断。结果筛查33 666例孕妇,筛查出21-三体高风险孕妇1246例,占3.70%,18-三体高风险孕妇316例,占0.94%,神经管畸形高风险417例,占1.24%,确诊21三体患儿10例,18-三体患儿3例,神经管疾病9例,经随访,发现4例21-三体患儿漏诊。结论孕中期产前筛查、诊断不失为一条降低先天性缺陷胎儿出生的有效途径。 Objective To explore the value of serum screening for Down’s syndrome in the second trimester of pregnancy to prevent birth defects. Methods Time-resolved immunofluorescence method was used to screen 33 666 pregnant women with 15-20 w pregnant women for further prenatal diagnosis of high-risk pregnant women. Results A total of 33 666 pregnant women were screened. Among them, 1246 pregnant women with high risk of trisomy 21 were found, accounting for 3.70%. 316 pregnant women with high risk of 18-trisomy, accounting for 0.94%, 417 were high risk of neural tube defects, accounting for 1.24% 21 trisomy in 10 children, 18 cases of trisomy in 3 cases, 9 cases of neural tube disease, after follow-up, found that 4 cases of 21-trisomy children missed. Conclusion The prenatal screening and diagnosis in the second trimester may be an effective way to reduce the birth of a fetus with congenital defects.