tokens: Methods A retrospective analysis ( 2001 - 2014 ) was conducted based on the National Congenital Malformation Registries network of Italy ( Emilia - Romagna Registry of Birth Defects [ IMER ] and Registro Toscano Difetti Congeniti [ RTDC ] ) , which were analyzed to investigate time trends , geographical / ethnic clusters , topography , sex ratio , and associated congenital anomalies of OC phenotypes .