Carbimazole embryopathy is a recently recognized and defined phenotype. Choanal atresia; gastrointestinal anomalies, particularly esophageal atresia; athelia or hypothelia; developmental delay; hearing loss; aplasia cutis; and dysmorphic facial features all can occur after exposure to the antithyroid drugs carbimazole or methimazole during gestation. Although full expression of this phenotype appears to be an uncommon sequelae of antenatal carbimazole exposure, infants with less overt manifestations may remain with the condition undiagnosed. It is clearly important when an infant with choanal atresia is assessed to take an adequate drug history and consider this embryopathy as a potential causative factor.
Wolf D, Foulds N, Daya H. Antenatal Carbimazole and Choanal AtresiaA New Embryopathy. Arch Otolaryngol Head Neck Surg. 2006;132(9):1009-1011. doi:10.1001/archotol.132.9.1009