What fetal risk is associated with the use of methimazole during pregnancy?

Methimazole is an antithyroid medication used to manage hyperthyroidism, and its use during pregnancy has been associated with specific fetal risks. One significant concern is aplasia cutis, which is a congenital condition characterized by the absence of skin in certain areas of the body. Research has shown an increased incidence of aplasia cutis in infants born to mothers who used methimazole during the first trimester of pregnancy. This relationship highlights the importance of careful consideration when prescribing methimazole to pregnant women or those planning pregnancy, as well as the need for monitoring and counseling regarding potential risks.

The other conditions listed, such as spina bifida and Down syndrome, are not specifically linked to methimazole exposure during pregnancy. While congenital heart defects can occur in various circumstances, they have not been directly correlated with methimazole in the same way that aplasia cutis has been documented. Understanding these risks helps healthcare providers make informed decisions about the management of hyperthyroidism in pregnant patients.