Is Down Syndrome a Disappearing Birth Defect?

Abstract

Objective: To assess trends in the prevalence of Down syndrome (DS) from 1986 to 2004 in Victoria, Australia (population ∼5 million). Study design: The Victorian Birth Defects Register and the Prenatal Diagnosis Database were linked to ascertain all cases of DS. Total and birth prevalence estimates were calculated per year and presented as 3-year moving averages. Results: The total number of cases of DS increased from 113 in 1986 to 188 in 2004. The number of births declined over the first decade of the study, particularly in younger women, but total numbers have fluctuated between 45 and 60 births since 1996. In women under age 35 years, total prevalence was 10/10,000 until 1997 and then in..