Studies of second trimester prenatal screening and diagnosis for Down's syndrome and open neural tube defects [Down's syndrome prenatal screen and diagnosis]

Objective: This study was to identify in the utilization of second trimester maternal serum screening and prenatal diagnosis of Down' syndrome and other congenital abnormality to pregnant women in regional Chongqing for reducing the frequency of natal defect.Methods: Detect the value of AFP and β-HCG in the serum of 13017 pregnant women at about 14th～20th weeks by ELISA and calculate their risk coefficient with professional computer software(The risk cut-off levels were 1:275 for Down's syndrome,2.5 MoMs alpha fetoprotein for open neural tube defects).Analyze karyotype in amniotic fluid and carry out gene diagnosis to Down's syndrome high risk pregnant women.Perform ultrasonography to neural tube defect(NTD) high risk cases.Results: In 13017 pregnant women,771 cases(5.92%) were high risk,607(4.66%) high risk cases of Down's syndrome,116(0.89%) high risk cases of NTD and 48(0.37%) high risk of 18 trisomy and 13 trisomy.According to further diagnosis,11 cases of 352 high risk pregnant women were abnormal pregnancies.5 cases of 48 trisomy 18, trisomy 13 high risk women were normal,the rests didn't accept further diagnosis,3 cases of them had been certified to abnormal pregnancies because the fetuses died in the womb.According to B-ultrasonography detection,3 cases of 116 NTD high risk cases were NTD fetus.Conclusion: Prenatal screen and prenatal diagnosis have very important significance to the prevention of Down' syndrome and other congenital abnormality.