[Plasma levels of PGE2, PGA2 and PGF2 alpha during spontaneous labour]

Plasma levels of PGE2, PGA2 and PGF2 alpha were determined by radioimmunoassay in maternal venous blood during different phases of uterine contractions. Mean prostaglandin levels during labor were: PGE2 = 2,25 +/- 1,3 ng/ml (mean +/- SD), PGA2 = 2,86 +/- 1,55 ng/ml and PGF2 alpha = 0,58 +/- 0,37 ng/ml. The approximate ratios between the prostaglandin concentrations were: PGE2:PGA2: PGF2 alpha = 1:1-3:0,3. No changes of PGE2 levels were found in the course of concentrations during the first and second stage of labor. At delivery and at the contraction followed by the expulsion of the placenta, PGE2 concentrations rose from the beginning of the contraction (2,21 +/- 0,07 ng PGE2/ml) to the maximum of the contraction (4,31 +/- 0,56 ng PGE2/ml). PGA2 levels did neither show a correlation to the course of contractions nor to the different stages of labor, but were considerably different between patients during the first stage of labor (e.g. 1,9 +/- 1,1 ng PGA2/ml) and during the second stage of labor (3,36 +/- 2,8 ng PGA2/ml). Mean PGF2 alpha concentrations were between 0,21 +/- 0,12 ngPGF2 alpha/ml (1st stage) and 0,81 +/- 0,11 ng PGF2alpha/ml (highest value obtained, 1st stage of labor, too). There was no correlation between PGF2 alpha concentrations and the course of contractions during the different stages of labor.