This is the fourth in a series of texts on fetal physiology and the changes occurring during the transitional period from intra- to extra-uterine life, a most critical and dangerous period in human life. The volumes in the series are each devoted to a particular system, the previous three volumes being devoted to the crucial areas of circulation, respiration and growth. The fourth volume follows the established format, considering first fetal development and perinatal changes, then pathophysiology and finally applying the information to clinical conditions. There is emphasis on the importance of basic research and animal models to clinical practice. The text therefore will appeal to a wide audience from undergraduate students of the basic sciences to clinicians working in the field of neonatal medicine. It is well presented and, in general, well illustrated.There are major differences in fluid balance between the fetus and adult. Apart from the fact that the fetus develops in a fluid environment, the tissues have a higher water content and overall the fluid shifts are greater. The text opens with a summary of the developmental stages of the kidney and the development of functional characteristics, in particular the endocrine function of the kidney and renally active hormones. Areas of current interest are highlighted including the ontogeny and regulation of water channels. Dynamics of fluid balance and the importance of the lymphatic system, fetal swallowing and exchange with amniotic fluid are considered in the next three chapters. More might have been said of transplacental flow and the altered fluid status of the mother. The section on basic physiology closes with a useful review of the changes in renal function observed at birth.The next section, that on pathophysiology, considers abnormalities in renal development whether as a result of congenital abnormalities, renal agenesis and obstructive uropathies or as a result of fetal growth retardation. The final chapter of this section is devoted to hydrops fetalis, a pathological increase of interstitial and total fetal body water. The many possible causes are reviewed.The final, clinical section centres on a detailed consideration of the management and correction of obstructive uropathies, fetal oedema, oligohydramnios and polyhydramnios. The relative advantages and disadvantages of available diagnostic and therapeutic interventions are comprehensively covered. The final chapter on management of postnatal disorders brings together many of the themes developed in earlier sections.This multiauthored book employs a wide range of expertise and presents critical consideration not found in standard texts. This fact, together with the focus on both basic science and practical aspects of fetal and neonatal medicine, makes the text a valuable source of reference. The production of a series of separate volumes rather than a single comprehensive text has resulted in relatively rapid publication with references up to 1996 being cited.