The thalidomide syndrome: risks of exposure and spectrum of malformations.

Echos of the 1959 to 1961 thalidomide disaster are still with us in the form of the continuing appearance, although more rarely, of similarly malformed children. A teratologic timetable could be fashioned retrospectively, supporting the concept that different body parts and systems have periods of vulnerability and of resistance to thalidomide, probably the most potent primate teratogen known. Something between one in every two to one in every ten fetuses exposed at the critical development period were affected. The clinical affects are described from the literature on approximately 2500 children, and from extensive personal experience, and a complex though finite pattern of malformations is described, indistinguishable from sporadic nonthalidomide cases of malformations that continue to occur.