Prenatal Screening Efficiency and Down Syndrome Incidence in St. Petersburg, Russia in the Years 2013–2023

BACKGROUND: Prevention of birth defects in children is a pressing issue. The total Down syndrome screening detection rate depends on the exact adherence to the prenatal examination algorithm and the average age of pregnant women. The introduction of new technologies increases the efficiency of chromosomal abnormality detection during total screening. AIM: The aim of this study was to assess the effect of organizational demographics on the frequency of births with chromosomal diseases, primarily Down syndrome, and to characterize additional factors to be taken into account when implementing a set of measures to prevent and avoid the birth of children with severe, uncorrectable and socially significant diseases. METHODS: This study included the results of a survey of 2,083 women in case of pre- and postnatal diagnosis of chromosome 21 trisomy in St. Petersburg, Russia from 2013 to 2023. Statistical data processing was carried out using standard software. RESULTS: We showed an increase in the average age of mothers and a decrease in the number of newborns in St. Petersburg over the specified period. The data on an increase in the efficiency of the prenatal diagnostics service were obtained, including using non-invasive prenatal testing for the group with an intermediate (from 1/101 to 1/1000) risk after combined screening. We also observed an increase in the timing of invasive diagnosis for prenatal karyotyping and the constant presence of a group of pregnant women who were not registered through city institutions and did not participate in preventive measures. CONCLUSION: From 2013 to 2023, the average incidence of Down syndrome (diagnosed pre- and postnatally) increased from 1/412 to 1/258 newborns. In general, the effectiveness of prenatal diagnosis increased to 94%; however, it is necessary to strive to transfer invasive diagnosis to earlier pregnancy. The average incidence of newborns with Down syndrome remains stable (1/1231).