The incidence of venous thrombosis in the general population is low, approximately 3 per 10 000 women per year among women in reproductive age. Despite the low incidence, use of hormonal... Show moreThe incidence of venous thrombosis in the general population is low, approximately 3 per 10 000 women per year among women in reproductive age. Despite the low incidence, use of hormonal contraceptives frequently causes venous thrombosis since millions of women worldwide use hormonal contraceptives. This use is associated with a two- to eight-fold increased risk of venous thrombosis, dependent on the type and dose of the contents of the hormonal contraceptive. The aim of this thesis was to study the risk of venous thrombosis during use of different hormonal contraceptives, focusing on the pathogenesis, the evaluation of a marker to estimate the risk of venous thrombosis, and the assessment of effectiveness, side effects including the risk of venous thrombosis and acceptability of a new hormonal contraceptive. Show less