Natural estrogen and anti-thrombin III activity in postmenopausal women.

Anti-thrombin III activity was measured in normal pre- and postmenopausal female controls: during late pregnancy, in young women taking oral contraceptives and in postmenopausal women treated with natural, conjugated estrogens. Both the pregnant patients and women on oral contraceptives had significantly lower anti-thrombin III levels when compared with the normal, untreated control group. Treatment with natural estrogens did not result in any alteration in anti-thrombin III activity. There was no significant difference in the anti-thrombin III values in the pre- and postmenopausal control subjects.