Haemostatic changes and the oral contraceptive pill

Area of Science:

• Thrombosis and Hemostasis
• Pharmacology of Oral Contraceptives

Background:

• Oral contraceptives (OCs) are associated with an increased risk of thrombovascular disease.
• This risk may be mediated by OCs' effects on the hemostatic system, influencing coagulation and fibrinolysis.

Purpose of the Study:

• To investigate the impact of oral contraceptives on the hemostatic system.
• To understand how estrogen and progestogen components influence coagulation and fibrinolysis.
• To assess the role of OCs in thrombus formation, considering other risk factors.

Main Methods:

• Review of studies examining hemostatic factors in oral contraceptive users.
• Analysis of changes in coagulation factors (VII, X, fibrinogen, antithrombin III).
• Assessment of fibrinolytic system components (plasminogen activator inhibitor I, plasminogen, tissue plasminogen activator).

Main Results:

• OC use increases coagulation factors (VII, X, fibrinogen) and platelet activity.
• Fibrinolytic activity also increases, potentially balancing procoagulant effects.
• Lower estrogen doses (20 mcg ethinylestradiol) demonstrate the least impact on hemostatic factors.

Conclusions:

• OCs enhance both coagulation and fibrinolytic activity, maintaining hemostatic balance.
• Thrombus formation risk is elevated with coexisting factors like vascular damage, age, or smoking.
• OC formulations with lower estrogen doses may offer a safer hemostatic profile.