In recent years there has been an impressive surge of interest in the mecha nisms which control the onset and the maintenance of labour. Much of it stems from a constant awareness that gestational age at birth is still an important factor in neonatal mortality and morbidity. Advances in the sensitivity and specificity of immunoassay, the discovery of the prosta glandins, new skills in fetal surgery and chronic catheterisation in experi mental animals have greatly stimulated further research in this area. In the meantime clinicians became continuously more aware that, despite consider able advances in perinatal medicine, gestational age at birth remains the major determinant of neonatal mortality and morbidity. It led them to seek new and better ways of controlling uterine function whether by influencing cervical ripeness, by stimulating or by inhibiting myometrial contractility. This volume uniquely combines knowledge which has been gained from both experimental and clinical research on parturition. A brief outline of current evidence on the control of parturition in experimental animals may be fruitful in delineating problems and hypotheses for further study in human pregnancy. Much of our present day knowledge of human parturition has been gained by checking such data against experimental findings, careful measurements and clinical observations in human pregnancy. It is hoped that the interdisciplinary nature of this volume will enhance the understanding of human parturition and stimulate further research in this area. Thanks are due to Miss H. Wittenberg and Mrs M."