Oxytocin and its receptor in pregnancy and parturition: current concepts and clinical implications.

OBJECTIVE: To present our current understanding of oxytocin and its receptors during pregnancy and parturition and their potential clinical applications. DATA SOURCES: A MEDLINE search was conducted for pertinent articles from 1966 to October 1996 related to oxytocin and its receptor and their clinical implications during pregnancy and parturition. Review articles, book chapters, and published trials were also searched. METHODS OF STUDY SELECTION: Only references in English that were deemed relevant were used. When possible, human data and sometimes animal data pertinent to understanding the interaction of oxytocin and its receptors were selected. TABULATION, INTEGRATION, AND RESULTS: Oxytocin is synthesized in the hypothalamus and in many reproductive tissues during pregnancy, whereas the receptors are synthesized in reproductive tissues. The genes for oxytocin and its receptors are on chromosomes 20 and 3, respectively. Oxytocin and its receptors are regulated by sex steroids and by oxytocin itself. The paracrine and autocrine mechanisms regulating oxytocin and its receptor within the fetoplacental-uterine unit are central to the control of uterine contractions and parturition. Such current understanding provides the basis for appropriate oxytocin regimens to induce or augment labor, to inhibit preterm labor by blockade of oxytocin receptors, and to achieve cervical ripening. CONCLUSION: Advances in our knowledge of oxytocin and its receptor have provided rational and sound principles for current concepts about their role in parturition, the appropriate use of oxytocin to stimulate the pregnant uterus or ripen the cervix, and the use of oxytocin antagonist to inhibit uterine contractions and preterm labor.