Environmental Factors

Thalidomide Infants

Until the early 1940s it was assumed that congenital defects were caused primarily by hereditary factors. With the discovery by Gregg that German measles affecting a mother during early pregnancy caused abnormalities in the embryo, it suddenly became evident that congenital malformations in humans could also be caused by environmental factors. In 1961 observations by Lenz linked limb defects to the sedative thalidomide and made it clear that drugs could also cross the placenta and produce birth...