Warkany was the first to prove that congenital developmental disorders can be induced by exogenous factors in mammals. His studies led to the definition of both genetic and environmentally induced structural defects. See also: Warkany, J. "Effect of maternal rachitogenic diet on skeletal development of young rat," Amer J Dis Child., 66 (1943) 511. 

Warkany's contributions span all aspects of teratology, both clinical and experimental. This has been called his magnum opus. It includes 124 chapters, each with detailed bibliography, on a total of 1271 pages.