Biochemical effects in women following one year's exposure to a new triphasic contraceptive--II. coagulation profiles.

1. Coagulation variables were determined in 14 contraceptive nonusers and 25 prior contraceptive users at 3, 6, and 12 months' exposure to a new oral form of progestin. 2. Overall hemostasis was unaffected, as was the intrinsic pathway. 3. Changes were noted in several vitamin-K dependent factors along with a marked decrease in fibrinogen. 4. Protein C antigen (a coagulation inhibitor), was elevated. 5. This new triphasic contraceptive appears to have a minimal influence on thrombosis while activating antithrombotic protein C. The data suggest a favorable hematologic response to this contraceptive.