Etiology of Malformations

HUMAN malformations have always been obobjects of speculation. In prescientific days they were regarded either as copies of things seen by the pregnant woman or as marks of bestial parentage or supernatural intervention. With the rise of biology these theories were abandoned, and the discovery of recessive inheritance encouraged the idea that the majority of malformations were genetically determined. More recently the opposite view —that most defects are caused by events after conception — has been gaining ground, as a result of experience with rubella and thalidomide in man and with various other teratogens in laboratory animals.The assumption underlying . . .