Analysis of prenatal screening and diagnosis test results in 7644 cases of second trimester of pregnancy

【Objective】To screen and diagnose Down's syndrome, neural tube defects and trisomy 18 syndrome during mid-term pregnancy to decreased the rate of birth defects. 【Methods】7644 women at 15-20 weeks gestation were screened by maternal serum AFP,β-hCG and uE3 using chemiluminescence, then to calculation the risk of fetal suffering from DS,NTD and trisomy 18 syndrome.【Resluts】Among the 7644 pregnant women, 421 were found to be at high risk with DS, by amniocentesis ,12 cases were diagnosed DS; 58 were found to be at high risk with NTD, by amniocentesis ,5 cases were diagnosed NTD; 51 were found to be at high risk with trisomy 18 syndrome, by amniocentesis ,1 cases were diagnosed trisomy 18 syndrome. 【Conclusions】Prenatal screening and prenatal diagnosis decreased the rate of birth defects.They have distinct social benefit, they are very effective technical means to carry out our country's prepotency policy.