- The aetiology of conotruncal heart defects is poorly understood and the birth prevalence varies geographically. The known risk factors for developing conotruncal heart defects are as follows: CHD in siblings, genetic chromosomal abnormalities, paternal age >30 years, high parity, low birth weight, prematurity, and maternal diabetes.The aim of this study was to characterise conotruncal heart defects, birth prevalence, mortality, and morbidity in the population of southern Israel, of whom 75% are Jewish and the rest are mostly Bedouin Arabs.The data were obtained from Soroka University Medical Center database of births and newborns. Conotruncal heart defects cases were identified by ICD9 codes.During 1991-2011, there were 247,290 singleton live births and 393 conotruncal heart defects in Soroka University Medical Center. The birth prevalence per 10,000 live births of tetralogy of Fallot, transposition of the great arteries, and truncus arteriosus was 9.5, 5, and 1.8, respectively. In the multivariate analysis, Bedouin descent (adjusted odds ratio 2.40, p35 years (1.66, p=0.004), and siblings with congenital heart defects (1.98, p=0.005) were associated with tetralogy of Fallot, and Bedouin descent (1.61, p=0.05), siblings with congenital heart defects (2.19, p=0.004), and diabetes mellitus (7.15, p<0.001) were associated with transposition of the great arteries. In a univariate analysis, Bedouin descent (p=0.004) and congenital heart defects in siblings (p<0.001) were associated with truncus arteriosus.We observed higher birth prevalence of conotruncal heart defects compared with the birth prevalence reported worldwide, specifically among the Bedouins, a population characterised with high consanguinity rate. Therefore, genetic counselling and early fetal echocardiograms should be encouraged, especially in high consanguinity rate populations. Naturally, further educational efforts are needed in order to decrease consanguinity and its related consequences.