There are a large number of teratogenic materials, Thalidomide is a well known example. The Rubella (German measles) virus is also teratogenic, as is use of large amounts of alcohol during pregnancy (Fetal Alcohol Syndrome).
The term teratogenesis refers to the production of congenital malformations, such as cleft lip and/or palate, anencephaly, ventricular septal defect, medically serious abnormalities present at birth. The term derives from teratology, the study of the frequency, causation, and development of congenital malformations--misleadingly called birth defects.