Increased serum levels of endogenous as well as exogenous estrogen are regarded to be responsible for acquired activated protein C (APC) resistance (which allows for longer duration of thrombin generation and may lead to a hypercoagulable state).
The sensitivity to activated protein C differs between the different phases of the menstrual cycle. Women without factor V Leiden were more likely to have lower normalized activated protein C sensitivity ratios at the beginning of the cycle than later on in the cycle (1.34 versus 1.54 and 1.58).
Among groups matched with regard to insulin-sensitivity markers, both monomeric hyperprolactinemia and macroprolactinemia appeared to promote platelet activation.
http://www.ncbi.nlm.nih.gov/pubmed/20960266
The adjusted odds ratio (OR) for venous thromboembolic disease (VTE) associated with current oral contraceptive use was 4.07. The OR associated with OC use was higher for women who were obese than in the nonobese and in women without predisposing medical conditions. The adjusted OR for VTE was 7.10 in women with factor V Leiden (G1691A) mutation, 2.83 in women with prothrombin G20210A mutation and 0.26 in women with the MTHFR C677T mutation. The OR for VTE in OC users with factor V Leiden mutation (11.32) was elevated more than in OC users without the mutation (3.20) and women with the mutation who were non-OC users (8.42), but confidence intervals overlapped.
Pregnancy increases the risk of thrombosis three-fold to four-fold. The hypercoagulability of pregnancy is present as early as the first trimester and so is the increased risk of thrombosis.
Exogenous estrogen-mediated thrombophilia superimposed on heritable thrombophilia and hypofibrinolysis is associated with arterial and venous thrombi, and appears to be a preventable, and potentially reversible etiology for ischemic optic neuropathy and ischemic stroke.
Patients with pulmonary embolism were younger (56.5 vs 60.9 years) and more likely to be female. The odds ratio for risk of PE was elevated for the following: female gender, prolonged immobilization, history of prior venous thromboembolism (VTE), lower extremity varicose veins, body mass index (BMI) > or = 25 kg/m( 2), extremity paralysis, and gout/hyperuricemia. Inherited thrombophilia was found in 14 patients with PE (14%).
Factor V Leiden and Miscarriage