Thalassemia is a great health burden in mainland China. Carrier screening and prenatal diagnosis (PND) are essential for its prevention. The aim of this study was to describe the trend in the timing of PND for thalassemia in at-risk families in mainland China. All women who were at-risk for thalassemia and received PND at a mainland Chinese tertiary obstetric center between 2011 and 2019 were included. Information required for the survey was obtained from the database of the institute. In total, 4045 women underwent PND for thalassemia, including 1720 for β-thalassemia (β-thal) and 2325 for α-thalassemia (α-thal). The median gestational age for the PND procedure was 13 weeks. The number of PNDs performed increased year by year over this period. For both β-thal and α-thal, the proportion of women undergoing early PND also increased along with the time span. A total of 428 cases was diagnosed prenatally to be affected with β-thal major (β-TM) and 769 were affected with Hb Bart's disease. Most of the β-TM pregnancies and all of the Hb Bart's disease pregnancies were terminated. With the implementation of effective screening measures, births of affected infants have been dramatically avoided, and early PND has become the main approach, thus allowing the possibility of obtaining results at an earlier stage of pregnancy.
Keywords: Gestational age; mainland China; prenatal diagnosis (PND); thalassemia.