Objective The screening information of 1 036 women in the second trimester of pregnancy in Shexian County were analyzed to understand the risk of fetal morbidity and to provide scientific basis for the prevention of birth defects. Methods Serum β- human chorionic gonadotropin (β-HCG),alpha fetoprotein (AFP) and free estriol (uE3) levels in mid-pregnancy women were detected by chemiluminescence immunoassay.These indicators calculated the risk rate of fetal morbidity by combining maternal age,weight,and gestational weeks. Results Of the 1 036 pregnant women screened,there were 61 cases (5.8%) in the high-risk group,43 cases (4.2%) in the borderline risk group,and 932 cases (90.0%) in the low-risk group.The pregnancy outcomes of 1 010 pregnant women were followed up,with 9 cases of therapeutic induced of labor.The differences of the therapeutic induced labor rates in different risk groups were statistically significance (χ²=9.984,P=0.006).There were 32 cases of combined gestational hypertension in pregnant women.Notably,the detection rate of hypertension in pregnancy was higher in the borderline risk and high risk groups than in the low risk group (χ²=5.432,P=0.045). Conclusion Serological screening in the second trimester of pregnancy has significant effect on the prevention of birth defects.