Blood levels of proteinase inhibitors in pregnancy.

Plasma volume, serum alpha 2-macroglobulin, alpha 1-antitrypsin, C1 inactivator and alpha 2-antiplasmin, and plasma antithrombin III were measured in 10 pregnant women at gestation periods of 12-14 and 37-38 weeks. The proteinase inhibitors were also measured in 10 non-pregnant healthy women. There was a significant increase in the alpha 1-antitrypsin concentration and significant decreases in alpha 2-macroglobulin and C1 inactivator, but the total circulating quantity of all the proteinase inhibitors was significantly increased.