[13, 14-Dihydro-15-keto-PGF2 alpha (PGFM) and progesterone serum levels in labor]

Progesterone and PGFM serum levels were estimated by RIA in patients with spontaneous and induced labor. Induction of labor was performed by amniotomy or by local application of prostaglandins. Mean progesterone serum levels were at 130 ng/ml at the time of admission into the labor-room, and declined to mean levels of some 50 ng/ml in all 3 groups of patients 30 minutes after placenta expulsion. Mean PGFM serum levels were 2,5 to 3,5 times higher in patients with spontaneous labor than in those in whom labor was induced. Parallel decline of progesterone and PGFM serum levels was noted in patients with spontaneous labor, whereas declining progesterone levels but increasing PGFM serum levels were observed in patients with induced labor. These data combine to suggest that an increase in PGFM serum levels may be the cause for the onset of labor. But, the question whether progesterone triggers these processes cannot be answered by the present observations.