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Haemostatic changes and the oral contraceptive pill.
Baillieres Clin Obstet Gynaecol. 1997 Sep; 11(3):545-64.BC

Abstract

Oral contraceptives have been linked to an increased incidence of thrombovascular disease. This may be mediated by their effects on the haemostatic system. An increase in the activity of coagulation Factors VII, X and fibrinogen occur with pill usage. Increased Factor VII levels are dependent on both the oestrogen and progestogen component of the oral contraceptive. A reduction in antithrombin III levels has also been observed in some but not all studies. Increased fibrinolysis has also been shown in oral contraceptive users which should balance the changes in the coagulation pathway. The increase in fibrinolytic potential is thought to be due to a decrease in the levels of plasminogen activator inhibitor I combined with an increase in the levels of plasminogen; tissue plasminogen activator antigen is decreased in most studies. The increased levels of endpoints of coagulation and fibrinolysis in pill users indicate that enhanced activity of both systems is occurring in vivo. The increased coagulation activity appears to be balanced by the rise in fibrinolytic activity, so preserving haemostatic balance. Enhanced platelet activity has also been shown in women taking oral contraceptives. Thrombus formation can result, however, when local vascular wall damage exists, or when other risk factors for thrombo-embolism, such as older age and smoking, coexist and create a local activation resulting in a thrombus. In these situations, the small differences in levels of coagulation factors in women taking different oral contraceptive formulations may be important. Pills containing the lowest doses of oestrogen (20 micrograms ethinyloestradiol) have shown the least changes in haemostatic factors. The progestogen component of the pill modifies the effect of oestrogen on the haemostatic system.

Authors+Show Affiliations

Department of Obstetrics and Gynaecology, St James's Hospital, Dublin, Ireland.No affiliation info available

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

9488791

Citation

Norris, L A., and J Bonnar. "Haemostatic Changes and the Oral Contraceptive Pill." Bailliere's Clinical Obstetrics and Gynaecology, vol. 11, no. 3, 1997, pp. 545-64.
Norris LA, Bonnar J. Haemostatic changes and the oral contraceptive pill. Baillieres Clin Obstet Gynaecol. 1997;11(3):545-64.
Norris, L. A., & Bonnar, J. (1997). Haemostatic changes and the oral contraceptive pill. Bailliere's Clinical Obstetrics and Gynaecology, 11(3), 545-64.
Norris LA, Bonnar J. Haemostatic Changes and the Oral Contraceptive Pill. Baillieres Clin Obstet Gynaecol. 1997;11(3):545-64. PubMed PMID: 9488791.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Haemostatic changes and the oral contraceptive pill. AU - Norris,L A, AU - Bonnar,J, PY - 1998/3/7/pubmed PY - 1998/3/7/medline PY - 1998/3/7/entrez KW - Biology KW - Blood Coagulation Effects KW - Contraception KW - Contraceptive Methods--administraction and dosage KW - Contraceptive Methods--pharmacodynamics KW - Diseases KW - Embolism KW - Family Planning KW - Fibrinolysis KW - Hematological Effects KW - Hemic System KW - Literature Review KW - Oral Contraceptives, Combined--administraction and dosage KW - Oral Contraceptives, Combined--pharmacodynamics KW - Oral Contraceptives--administraction and dosage KW - Oral Contraceptives--pharmacodynamics KW - Physiology KW - Risk Factors KW - Thromboembolism KW - Thrombosis--etiology KW - Vascular Diseases SP - 545 EP - 64 JF - Bailliere's clinical obstetrics and gynaecology JO - Baillieres Clin Obstet Gynaecol VL - 11 IS - 3 N2 - Oral contraceptives have been linked to an increased incidence of thrombovascular disease. This may be mediated by their effects on the haemostatic system. An increase in the activity of coagulation Factors VII, X and fibrinogen occur with pill usage. Increased Factor VII levels are dependent on both the oestrogen and progestogen component of the oral contraceptive. A reduction in antithrombin III levels has also been observed in some but not all studies. Increased fibrinolysis has also been shown in oral contraceptive users which should balance the changes in the coagulation pathway. The increase in fibrinolytic potential is thought to be due to a decrease in the levels of plasminogen activator inhibitor I combined with an increase in the levels of plasminogen; tissue plasminogen activator antigen is decreased in most studies. The increased levels of endpoints of coagulation and fibrinolysis in pill users indicate that enhanced activity of both systems is occurring in vivo. The increased coagulation activity appears to be balanced by the rise in fibrinolytic activity, so preserving haemostatic balance. Enhanced platelet activity has also been shown in women taking oral contraceptives. Thrombus formation can result, however, when local vascular wall damage exists, or when other risk factors for thrombo-embolism, such as older age and smoking, coexist and create a local activation resulting in a thrombus. In these situations, the small differences in levels of coagulation factors in women taking different oral contraceptive formulations may be important. Pills containing the lowest doses of oestrogen (20 micrograms ethinyloestradiol) have shown the least changes in haemostatic factors. The progestogen component of the pill modifies the effect of oestrogen on the haemostatic system. SN - 0950-3552 UR - https://www.unboundmedicine.com/medline/citation/9488791/Haemostatic_changes_and_the_oral_contraceptive_pill_ DB - PRIME DP - Unbound Medicine ER -