It is not known specifically what causes choanal atresia. The condition occurs when the thin tissue membrane in the back of the nasal airway that separates the nose and mouth as the fetus develops remains after birth. The tissue creates a partial narrowing or a complete blockage of the nasal airway.
Because the causes are unknown, risk factors for choanal atresia cannot be determined. Some specialists believe the abnormality relates to a disruption in the mother’s hormones. Recent studies point to exposure to herbicides as one of the likely risk factors of choanal atresia. Gender may play a role as choanal atresia affects nearly twice as many girls as boys. The condition may also arise as a result of CHARGE syndrome, a disorder that causes abnormalities in various parts of the body.