The purpose of this study is to describe the incidence of thromboembolic events in relation to pregnancy and when in pregnancy and the puerperal period.

Venous thromboembolism (VTE) still causes maternal death in the western world. The purpose of this study is to estimate the relative and absolute risk of VTE at different gestational ages in pregnant women compared to non-pregnant women.

All Danish Women 15 to 49 years old in the period January 1995 through December 2005, free of previous VTE and current use of oral contraceptives are included.Non-pregnant women are controls.

Inclusion Criteria:

• Danish woman at 15 to 49 years old in the period January 1995 through December 2005.
• Free of previous VTE and current use of oral contraceptives.

Exclusion Criteria:

• Previous VTE or current use of oral contraceptives.

Danish Women 15 to 49 years old in the period January 1995 through December 2005, free of previous VTE and current use of oral contraceptives.