The purpose of the research is to develop understanding of the causes of spontaneous abortion and of the types of fetuses that abort, in order to extend our current limited perspective on the epidemiology of congenital anomalies. At the individual level, we intend to provide a basis for improved reproductive counselling. At the population level, our aim is to develop procedures for monitoring spontaneous abortions so as to provide a new and powerful strategy for the detection of teratogens in the environment.