Prostaglandin F2alpha and E1 in plasma and amniotic fluid during human pregnancy and labor.

In order to elucidate the significance of PGs in human labor, PGE1 and F2alpha in biological fluid during human pregnancy and labor were measured by RIA newly developed. Analytical studies demonstrated that the levels of PGF2alpha in maternal plasma were 3.7 +/- 2.5 ng/ml a few days before parturition, 2.0 +/- 0.9 ng/ml in the first stage of labor and 1.9 +/- 1.4 ng/ml at delivery. Thus the concentrations of PGF2alpha in maternal plasma showed no significant changes around parturition. On the otherhand, the level of PGF2alpha in amniotic fluid represented a significant increase up to 44.27 +/- 32.81 ng/ml at delivery from 1.45 +/- 0.76 ng/ml before labor at 38-40 weeks of pregnancy (p less than 0.05), although it was uncertain whether this elevation was the cause or effect of uterine contraction. The concentration of PGE1 ranged from 2 to 14 ng/ml around parturition. This indicates that there was little remarkable difference between the levels of PGE1 in plasma and amniotic fluid during the last month of pregnancy and labor. Possible involvement of prostaglandins (PGs) in human labor has been discussed.