Progestational agents and blood coagulation. VII. Thromboembolic and other complications of oral contraceptive therapy in relationship to pretreatment levels of blood coagulation factors: summary report of a ten-year study.

During a ten-year period, 348 women were studied for a total of 5,877 patient months in four separate studies relating oral contraceptives to changes in hematologic parameters. Significant increases in certain factors of the blood coagulation and fibrinolysin systems (factors I,II,VII,VIII,IX, and X and plasminogen) were observed in the treated groups. Severe complications developed in four patients. All four had an abnormal blood coagulation profile, suggesting "hypercoagulability" before initiation of therapy. Some of these findings represented the most extreme abnormalities seen in the entire group of patients; some increased further during therapy. One of these patients developed a myocardial infarction before receiving any medication, shortly after the base-line values were obtained. One patient developed retinopathy 19 months after she began therapy, and another developed thrombophlebitis after 27 months of therapy. The fourth patient developed thrombophlebitis 14 days after initiation of contraceptive therapy. All four patients were of the A or AB blood group. Previous studies suggested the possiblility of increased propensity for thromboembolic episodes in patients possessing the A antigen. It appears from these data that hematologic work-ups may be useful in women who are about to start long-term oral contraceptive therapy.