[Analysis of Down syndrome screening by maternal serum detection in mid-pregnancy].
To study the clinical value of screening chromosomal diseases and abnormal pregnancy by maternal serum examination in mid-pregnancy. Maternal serum AFP and F-beta hCG were detected in the mid-pregnancy (16-20 weeks) using commercially available detection kits, and the risk of Down syndrome was calculated taking into account of such factors as the maternal age, gestational age, and body weight. Those at high risk underwent amino fluid or cordocentesis for fetal karyotpying. The pregnant women were divided into >or=35 years and <35 years groups, and high and low risk for Down syndrome groups for test results and pregnancy outcome analysis. Of the 6000 pregnant women undergoing antenatal screening, 552 were identified to be at high risk of Down syndrome (9.2%) with one missing case of detection, and 463 of the high-risk cases underwent amino fluid or cordocentesis examination. Twenty-seven cases were found to have abnormal chromosomes, and abortion was suggested in 14 cases but not in the other 13 cases where other chromosomal abnormalities such as polymorphic mutations were found. The screening positive rate in >or=35 years and <35 years group was 95.5% and 8.2% (P<0.0001), with fetal chromosomal abnormality rate of 4.5% and 2.9%, respectively (P>0.5). The rate of abnormal pregnant outcomes for high and low risk groups was 5.6% and 0.05% (P<0.0001), with pregnancy complication rate of 11.8% and 3.7% (P<0.0001) and fetal chromosomal polymorphic mutation rate of 2.8% and 1.1% (P>0.5), respectively. Maternal serum AFP and F-beta hCG levels in second trimester have important values in predicting fetal chromosomal diseases, and their detection may help reduce the birth defect rate and prevent abnormal pregnancy outcomes and complications.