Plasma fibrinogen in women: relationships with oral contraception, the menopause and hormone replacement therapy.

Plasma fibrinogen was measured in 4837 women aged 25-64 years as part of the Scottish Heart Health Study and Scottish MONICA population surveys. The relationships of oral contraceptive use, the menopause and hormone replacement therapy were examined. Univariate analyses found that women with a history of oral contraceptive use, premenopausal women and those on hormone replacement therapy all had significantly lower fibrinogen levels than women who had never used oral contraceptives, postmenopausal women and non-hormone replacement users respectively. These differences persisted after age standardization. On multivariate analysis, menopausal status and hormone replacement therapy had independent effects on fibrinogen levels. Together with the common risk factors, 9.9% of the total variation in plasma fibrinogen levels was explained. However, less than 1% of this was from the combined menopausal and hormonal factors. These results confirm a postmenopausal rise in fibrinogen level which may be relevant to an increased risk of coronary heart disease. In addition, a protective effect with hormone replacement therapy is noted, although this was probably due to selection bias.