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The effect of oestrogen dose and progestogen type on haemostatic changes in women taking low dose oral contraceptives
Author(s) -
Norris L. A.,
Bonnar J.
Publication year - 1996
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1996.tb09716.x
Subject(s) - progestogen , medicine , endocrinology , estrogen
Objective To determine the effect of oestrogen dose and progestogen type on the coagulation and fibrinolytic systems of a group of normal healthy women taking three different oral contraceptive combinations. Design Plasma levels of factor VII, X, antithrombin III, protein C, fibrinogen, tissue plasminogen activator activity, plasminogen activator inhibitor I antigen and fibrin (D‐dimer) degradation products were measured at pretreatment, 6, 14, 22 weeks of treatment and at 6 weeks post‐treatment in a group of 67 women taking either 30 μg ethinyloestradiol/150 μg desogestrel ( n = 21 ), 20 μg ethinyloestradiol/150 μg desogestrel ( n = 24 ), 30 μg ethinyloestradiol/75 μg gestodene ( n = 22 ). Participants Sixty‐seven healthy normal women, 18 to 34 years, smoking fewer than 15 cigarettes per day. The subjects were within 10% of their normal body weight and had no history of thromboembolic disease. Setting Coombe Women's Hospital and St James's Hospital, Dublin, Ireland. Results Factor VII and X levels were significantly raised on treatment with both the 30 μg ethinyloestradiol/desogestrel and gestodene combinations. Higher levels of factor VII activity were observed in the 30 μg ethinyloestradiol/desogestrel combination compared with the gestodene combination. Factor VII and X were not significantly affected by the 20 μg ethinyloestradiol combination. Increased plasminogen, fibrinogen and D‐dimer levels and decreased plasminogen activator inhibitor 1 antigen levels were observed during the treatment phases in all three groups. Antithrombin TI1 and protein C activity did not change during treatment with any of the oral contraceptives studied. Conclusions Low dose oral contraceptives cause an activation of the coagulation system which is balanced by an activation of the fibrinolytic system. Reducing the dose of ethinyloestradiol from 30 μg to 20 μg reduces the effect on factor VII and X. This effect can be modified by the progestogen. The lesser effect of the 20 μg combination may make this a safer option for some women than pills containing a higher dose of oestrogen.