Comparison of plasma prostaglandins in the non-pregnant and pregnant women: a longitudinal study.

Plasma levels of PGE2 and PGF2 alpha were determined in women from 24 to 40 weeks of pregnancy with non-pregnant women as controls. The plasma levels of PGE2 showed no significant changes as gestation advanced except for late pregnancy only. Furthermore, there were no significant differences observed between the control and pregnant subjects except late in pregnancy. On the other hand, the concentrations of PGF2 alpha in the pregnant subjects revealed a significant increase (p less than 0.005) compared with those of the controls, though no significant changes were observed with the advance of gestation except for late pregnancy. The PGF2 alpha/PGE2 ratio showed a six to ten times rise during pregnancy (p less than 0.005) compared with that of the controls. Therefore, the results obtained in the present study may explain the effectiveness of prostaglandin synthetase inhibitors in suppressing preterm uterine contraction and they also indicate the involvement of some factors in the initiation and inhibition of the myometrium contraction.