Surprisingly, the beginning of a modern approach This collection of articles and commentaries is an to the problems of birth defects is relatively recent integration of information from many disciplines, and dates from Gregg's classical report in 1941 that and presents a comprehensive survey of both recent mothers who contracted rubella during the first tri­ and previously reported work related to the major mester of pregnancy gave birth to infants with severe aspects of birth defects. In particular, an attempt multiple anomalies. For the first time, an environ­ has been made to provide a critical assessment of mental agent was found to be teratogenic in man current concepts and to identify areas in need of and was documented in a thoroughly convincing further investigation. manner. Since then, many important discoveries The scope of this volume and space limitations and significant developments have been made, par­ precluded discussion of and reference to all papers ticularly in the areas of environmental teratogenesis, of relevance or importance: a work of the present hereditary mechanisms, and prenatal diagnosis. nature must necessarily be selective. Some good In recent years, there has been an impressive papers have been left out or given relatively little surge of interest in the causes and prevention of consideration. It is my hope that the list of Further birth defects. Undoubtedly this resulted not only References will be consulted and should compensate from the thalidomide tragedy, but also from the for this lack of completeness.