Inclusion Criteria:  Group 1:  Pregnant and seeking abortion Gestation of pregnancy less than 10 weeks Healthy, no medical conditions  Group 2:  Pregnant and seeking abortion Gestation of pregnancy between 10 and 14 weeks Healthy, no medical conditions  Group 3:  Pregnant and seeking abortion Gestation of pregnancy between 14 to 20 weeks Healthy, no medical conditions  Group 4:  Non pregnant Healthy, no medical conditions Able to speak English independently  Exclusion Criteria:  All groups:  Unable to give informed consent Previous or current venous thromboembolism Current smoker Personal or family history of thrombophilia or haemophilia Taking medicines known to affect clotting parameters (e.g. Aspirin)  Groups 1-3:  - Planning to commence hormonal contraception prior to second blood test.  Group 4:  - Using hormonal contraception at baseline visit