tokens: The prevalence rates of the most common birth defects over the study period were ; septal defect ( 138.2 per 10,000 ; 95 % CI : 136.9-139.5 ) , congenital hip dislocation ( 652 per 10,000 ; 95 % CI : 64.1-65.9 ) , and ventricular septal defect ( 62.62 per 10,000 ; 95 % CI : 61.7-63.5 ) .