Changes in the Plasma Prostaglandin F_2α Metabolite before and during Spontaneous Labor and Labor Induced by Amniotomy, Oxytocin and Prostaglandin E₂

Abstract

To elucidate the role of endogenous prostaglandin F_2αin spontaneous and induced labor, plasma concentrations of13, 14-dihydro-15-keto-prostaglandin F_2α (PGFM) were determined before the onset of labor, at onset of labor, during active labor, at the crowning of the fetal head, and 1 and 2 hours after delivery. Patients in spontaneous labor and labor induced by amniotomy, oxytocin, and prostaglandin E₂were studied. The levels of plasma PGFM in patients who entered spontaneous labor fell2to3weeks before delivery, whereas those in the induced labor group did not change until the time of induction. Although the levels of PGFM rose gradually with the progress of labor in all cases, the levels in the spontaneous labor were significantly lower in each stage than in the corresponding stage of induced labor. These results suggest that endogenous prostaglandin F_2α (PGF_2α) production decreases2-3 weeks prior to the spontaneous onset of labor and is increased again as labor progresses, that the patterns of PGF_2αproduction are similar to each other during spontaneous labor and labor induced by various methods. Therefore, it is felt that endogenous PGF_2α may participate in the progress of all kinds of labor.