Objective To analyze the results of prenatal screen and diagnosis of thalassemia in 4438 pregnant women.Methods Quantitation of hemoglobin and thalassemia genetic analysis were used for screening thalassemia in 2219 couples.The couples carring thalassemia genes were suggested to take some related prenatal examinations.After permission,amniotic fluid or chorionic villi samples,and umbilical vein blood were collected from early and middle-late gestation respectively for the detection of thalassemia gene.Results Mild alpha-thalassemia gene carrier and mild beta-thalassemia gene carrier in one person of the couple were found in 221 cases(4.98%) and 133 cases(3.00%) respectively;thalassemia gene was found in both husband and wife in 13 couples.Of the 13 couples,11 agreed to make prenatal diagnosis and 5 foetus of them were diagnosed as heavy thalassemia.Conclusion Prenatal screen and diagnosis in pregnant women can be used to diagnose the fetus with intermediate and severe thalassemia.