Carbimazole is metabolized to methimazole, which interferes with the production of thyroid hormones. Its use in hyperthyroid women during pregnancy can result in embryopathy.
Malformations that can be seen with carbimazole/methimazole exposure:
(1) bilateral choanal atresia
(2) tracheoesophageal fistula
(3) ventricular septal defect or other congenital heart malformation
