[Plasma factors regulating prostacyclin synthesis during pregnancy].

Prostacyclin is the most potent endogenous inhibitor of platelet aggregation known so far, produced by endothelial and smooth muscle cells. This substance is assumed to play a key role in maintaining a sufficient blood flow in maternal and fetal circulation. There is now some evidence that there is a non-cellular component in human blood, which is able to influence the prostacyclin formation to a certain degree, the so-called "prostacyclin synthesis stimulating plasma factor". A change in the plasma factor activity in patients with a disturbance of PGI2 metabolism has been observed. We examined the activity of this plasma factor during pregnancy and one year after delivery. During the first and second trimenon increased values were observed, whereas at the end of pregnancy the values were significantly decreased. The values for plasma factor activity one year after delivery were comparable to those of the control group. In patients with diabetes mellitus decreased activity of the plasma factor was observed, but its course was similar to that seen in normal pregnancy.