CHANGES IN FIBRINOLYTIC PARAMETERS AFTER DELIVERY
Recent studies by Astedt et al. have shown increasing levels of plasminogen activator inhibitor during pregnancy, but the origin of the inhibitor is unknown. Levels of fibrinolytic parameters were determined in plasma collected from 18 females (age 22.7 ± 3.2, mean ± SD) after a normal medically controlled pregnancy at the time of delivery and on the following 5 days. Tissue-type plasminogen activator (tPA) antigen was measured by enzyme immunoassay, urokinase type plasminogen activator (uPA) antigen by a radioimmunoassay and plasminogen activator inhibitor (PAI ) by a functional assay. The results are summarized in the following table:Postpartal changes in tPA antigen and PAI have been found to be significant, both decreasing after delivery and reaching normal control values for tPA on day 2 and for PAI on day 1 while uPA antigen remained normal. Since tPA levels before delivery have been found to be normal, increased levels at delivery might be caused by a release or by hormonal changes, while the decrease in PAI might again be caused by hormonal changes or by removal of the placenta.