Increasing incidence of the Down syndrome in the Czech Republic: Long-term population-based study

Abstrakt

ABSTRACT No. P18.17A. INTRODUCTION: Down syndrome is the most common chromosomal aneuploidy syndrome, therefore it is one of the main targets for the prenatal screening/diagnostics programmes worldwide. The main goal for this study was to investigate the effect of increasing maternal age (the result of the known and ongoing demographic change in the Czech Republic) on the population incidence of Down syndrome. METHODS: Data were obtained from the official National Registry of Congenital Anomalies of the Czech Republic. We evaluated the incidence of Down syndrome (ICD-10 code Q90) in the livebirths and in the prenatally diagnosed cases (time period 1994-2017). We were also investigating other related variables (like maternal age, diagnostic/screening methods). The registration process is country-wide and compulsory by national law. RESULTS: The overall incidence of Down syndrome in livebirths decreased from 7.79 in 1994 (relative incidences per 10.000 live births) to 3.48 in 2017 (p<0.05). The incidence of prenatally diagnosed (and electively terminated) cases increased rapidly from 5.35 in 1994 to 25.53 in 2017 (p<0.05). The average maternal age increased from 22.9 in 1994 to 30.2 in 2017. DISCUSSION: The overall incidence of Down syndrome in the Czech Republic is increasing (the incidence is increasing in prenatally diagnosed and terminated cases, the incidence in births is decreasing). We identified two main reasons: 1) gradual implementation of combined screening of the first trimester; 2) rapidly increasing maternal age in the Czech Republic during the last 30 years.