The first edition of this book appeared at a time when, for 50 years, there had been no attempt to bring together information concerning pathologic changes found in the fetus and infant or the physiologic processes which, by their rapid change during this age period, are often responsible for or associated with abnormal states. It is interesting that two books concerned with this subject were published almost simultaneously in 1952 and it seems probable that they were responsible in some measure for stimulating interest in this period of life and for the subsequent increase in number of investigations concerned with normal and abnormal processes related to fetal development and the establishment of an extrauterine existence that have appeared since then.