ABSTRACT
This chapter examines how prostaglandin biosynthesis is regulated within the uterus and provides more detailed information on regulation by cytokines which may be of particular importance in the onset and progression of preterm labor. The formation of prostaglandins and thromboxanes begins with the action of prostaglandin endoperoxide synthase, synonymous with fatty acid cyclooxygenase, on arachidonic acid. The presence of prostaglandins in amniotic fluid was reported first by S. M. M. Karim, and shortly thereafter he also observed that labor was associated with greatly increased concentrations of prostaglandins in amniotic fluid of women at term of pregnancy. The mechanisms responsible for increased prostaglandin concentrations in amniotic fluid during labor are functional prior to term because preterm labor and therapeutic abortions are associated with elevated levels of amniotic fluid prostaglandins. Such mechanisms are highly responsive, because prostaglandin concentrations in amniotic fluid can increase within minutes.
