The prevalence of live birth Down syndrome in the region of Primorsko-goranska County in Croatia, 1996-2005: the impact of screening and amniocentesis.

Objectives: To investigate the prevalence of live birth Down syndrome (DS) in the region of Primorsko-goranska County (PGC) in Croatia from 1996 to 2005 and to evaluate the impact of second-trimester maternal serum screening (MSS) and amniocentesis on live birth DS prevalence.
Methods: Study was based on databases from the Department of Gynecology and Obstetrics, University Hospital Centre Rijeka, the Department of Biology and Medical Genetics, School of Medicine, University of Rijeka, and the Croatian National Institute of Public Health. The regional policy of prenatal diagnosis for DS includes amniocentesis for pregnant women aged 35 or over and MSS for younger women. We estimated live birth and total prevalence of DS and measured the proportion of pregnant women using MSS and amniocentesis. Trends of live birth and total prevalence of DS were tested by linear regression analysis.
Results: The live birth prevalence of DS was 1.4/1000 in the period 1996-2005. A decreasing, but nonsignificant, trend of prevalence was observed over time (P = 0.577). Women aged 35 or over represented 11.6% of all pregnant women included in the study. The proportion of women who had MSS was 33.9%. The proportion who underwent amniocentesis was 6.1%.
Conclusions: No marked decrease in prevalence of live birth DS was observed in the region of PGC during the last 10 years. The usage of MSS and amniocentesis was too low to have any significant impact on live birth DS prevalence. Women's, as well as physician's, knowledge and attitudes towards prenatal diagnosis of DS should be evaluated.