[Possible teratogenic effects of thiamazole].

A newborn male presented with choanal atresia and minor dysmorphic facial features. At 4 years of age he showed delayed speech and language development. His mother had been treated with thiamazole for pre-existing hyperthyroidism during the first 3 months of pregnancy. It is possible that the maternal use of thiamazole caused the congenital anomalies. Embryopathy caused by maternal thiamazole use during pregnancy has been described several times before and is mainly characterised by choanal atresia, oesophageal atresia, minor dysmorphic facial features, growth retardation and delayed psychomotor development. Because the use of propylthiouracil during pregnancy has not been associated with similar effects, it is the treatment of choice for hyperthyroidism during pregnancy. For pregnant women or women who wish to become pregnant, thiamazole should be prescribed only ifpropylthiouracil cannot be used.