Epidemiological Characteristics and Maternal Risk Factors of Microtia and Aural Atresia in Kazakhstan.

 Microtia and aural atresia present congenital ear anomalies that affect external ear and are associated with conductive hearing loss. Both anomalies result from exposure to various prenatal risk factors, most common during the first trimester of pregnancy.  This study was aimed at epidemiological analysis of microtia/atresia and associated risk factors in the Kazakhstani population.