[The physiological importance of prostaglandins in the mechanism of human labor].

Recent results indicate that prostaglandins play a major role in the mechanism of human labor. There are, however, no systematic studies on the role of prostaglandins in various forms of induction of labor. In the present study the concentration of 13,14-dihydro,15-ketoprostaglandin F2 (PGFM) in the maternal peripheral plasma was determined in labor of spontaneous onset, in labor after induction with oxytocin and in labor after induction by artificial rupture of membranes (ARM). In an additional group of women PGFM was determined before and immediately after delivery to get an insight into the mechanism of placental separation. In labor of spontaneous onset PGFM concentration increased significantly. In labour induced by oxytocin PGFM levels rose only in those women in whom induction of labor was successful. In induction of labor by ARM, PGFM level also increased in all women in whom induction was successful. At the time of placental separation PGFM concentration in the maternal blood increased dramatically. From the result of this study it is concluded that the increase of prostaglandin F synthesis is a necessary prerequisite for vaginal delivery and that prostaglandins are of major importance in the mechanism of placental separation and expulsion.