Protein C levels in late pregnancy, postpartum and in women on oral contraceptives

Abstract

4 groups of 30 women participated in a study designed to examine the protein C level during late normal pregnancy, the puerperal period, and oral contraceptive (OC) use. The results were compared with those obtained with another important inhibitor, i.e., antithrombin III. In pregnant women, protein C levels during the 3rd trimester of normal pregnancy were the same as those in control nonpregnant women. Delivery did not induce any variations in protein. Antithrombin III was slightly decreased in late pregnancy, the decrease being more important at 24 hours following delivery. The women using OCs showed a significant increase in protein C compared with the control group; antithrombin was similar in both groups. The results show that protein C levels were not altered in the 3rd trimester of normal pregnancy and in the immediate postpartum period and make it difficult to assign an important role to protein C in the mechanism responsible for the increased rick of thrombosis observed in these situations. The data also eliminate the possibility that the risk of thrombosis observed in OC users could be due to a decrease in protein C.