Historical documents concerning craniopagi and conjoined twins.

The occurrence of congenital malformations had been documented by the Assyrian and Babylonians about 2,800 B.C. Historically, a significant source of information concerning conjoined twins were the so called "fugitive sheets" which following the introduction of printing served to disseminate news. The first sonographs with descriptions of congenital defects in human and animals appeared during the 17th century. Teratology became established during the 19th century as a result of the fundamental discoveries in embryology. Significant impetus was given to teratological research in this century following the discovery of GREGG (1941), from observations of the children born to pregnant women who were exposed to the atomic bombs, as well as the thalidomide catastrophe.