Which congenital anomalies are associated with folic acid antagonists?

Folic acid antagonists, such as certain medications used to treat conditions like epilepsy and cancer, can interfere with the normal metabolism of folate. Folic acid is crucial during early pregnancy for proper neural tube closure and development. When folic acid antagonists are used, particularly in the periconceptional period, they can lead to an increased risk of congenital anomalies, notably congenital heart defects.

Congenital heart defects occur due to the improper formation of the heart and major blood vessels, which can be influenced by nutritional deficiencies and teratogenic effects associated with the lack of adequate folate. Hence, exposure to folic acid antagonists in early pregnancy has been linked to these specific heart defects due to disrupted embryological development.

While other congenital anomalies, such as spina bifida, are associated with folate deficiency, the direct connection of folic acid antagonists with congenital heart defects is a more established link in the context of this question.