During the mid- to late-twentieth century, study of the physiology of the developing fetus and newborn infant evolved rapidly to become a major discipline in the biomedical sciences. Initially of interest from a standpoint of function of the placenta and oxygenation of the fetus, the field advanced to explore both normal functional mechanisms as well as pathophysiologic aspects of their regulation. Examples include studying the role and regulation of circulatory vascular anatomic shunts in oxygenation, cardiac function, certain aspects of asphyxia in the fetus and newborn infant, the role of fetal “breathing� movements, cyclic electroencephalographic activity, and analysis of electronic monitoring of fetal heart rate variability and its significance. Included in this book are reminisces of several dozen individuals who played a vital role in these developments. Overall, this survey considers a number of aspects of the development of the science of fetal and neonatal physiology, and its role in the greatly improved care of pregnant women and their newborn infants. This book is published on behalf of the American Physiological Society by Springer. Access to APS books published with Springer is free to APS members.