Pregnancy-induced<unk>  is probably a physiologically adaptive mechanism to prevent post partum hemorrhage. Pregnancy changes the plasma levels of many clotting factors, such as fibrinogen, which can rise up to three times its normal value. Thrombin levels increase. Protein S, an anticoagulant, decreases. However, the other major anticoagulants, protein C and antithrombin III, remain constant. Fibrinolysis is impaired by an increase in plasminogen activator inhibitor-1 (PAI-1 or PAI) and plasminogen activator inhibitor-2 (PAI-2), the latter synthesized from the placenta. Venous stasis may occur at the end of the first trimester, due to enhanced compliance of the vessel walls by a hormonal effect. Also, pregnancy can cause<unk>  by other factors, e.g. the prolonged bed rest that often occurs post partum that occurs in case of delivery by forceps, vacuum extractor or Caesarean section. A study of more than 200,000 women came to the result that admission to inpatient care during pregnancy was associated with an 18-fold increase in the risk of venous thromboembolism (VTE) during the stay, and a 6-fold increase in risk in the four weeks after discharge, compared with pregnant women who did not require hospitalization. The study included women admitted to hospital for one or more days for reasons other than delivery or venous thromboembolism. Pregnancy after the age of 35 augments the risk of VTE, as does multigravidity of more than four pregnancies. Pregnancy in itself causes approximately a five-fold increased risk of deep venous thrombosis. Several pregnancy complications, such as pre-eclampsia, cause substantial<unk> .<unk>  states as a pre-existing condition in pregnancy include both acquired ones, such as antiphospholipid antibodies, and congenital ones, including factor V Leiden, prothrombin mutation, proteins C and S deficiencies, and antithrombin III deficiency.
Hypercoagulability in pregnancy
High-risk pregnancy
Pre-existing disease in pregnancy
Complications of hypertension
Hypertensive disease of pregnancy
Early pregnancy bleeding
Complications of pregnancy
Anemia in pregnancy