The authors' review of studies on the teratogenicity of lithium salts during pregnancy revealed conflicting evidence. They believe lithium therapy should be initiated during pregnancy only in severely manic women who are unresponsive to other therapy and for whom continuing manic behavior would jeopardize their own or their babies' lives. They offer six cautions in the use of lithium during pregnancy, including avoidance of diuretics and of salt restriction. In addition, they announce the formation of an American Registry of Lithium Babies.