Meade T W, Haines A P, North W R, Chakrabarti R, Howarth D J, Stirling Y
Lancet. 1977 Nov 5;2(8045):948-51. doi: 10.1016/s0140-6736(77)90888-1.
In 15 women on oral contraceptives containing 30 microgram oestrogen, mean values for factors II, VII, and X, fibrinogen, fibrinolytic activity, antithrombin III, cholesterol, and fasting triglycerides were intermediate between values for 63 women on preparations containing 50 microgram oestrogen and those for 243 premenopausal women not on oral contraceptives. Mean blood-pressure levels, however, were higher in women on 30 microgram than in those on 50 microgram preparations. In 28 women on 50 microgram preparations containing 3 mg or 4 mg norethisterone, mean values of factor VII, fibrinogen, fibrinolytic activity, cholesterol, fasting triglycerides, and systolic blood-pressure were higher than in 15 women whose preparations contained only 1 mg of norethisterone. A less consistent picture was found in women on 30 microgram oestrogen preparations containing either 250 microgram (10 women) or 150 microgram (5 women) d-norgestrel. It is concluded that 30 microgram oestrogen preparations probably result in smaller hemostatic and lipid changes than 50 microgram preparations but that they may have a blood-pressure-raising effect attributable to the particular progestagen, d-norgestrel, used in 30 microgram preparations. The safety of these 30 microgram oestrogen preparations may thus depend partly on the balance between these two sets of effects. It is also concluded that norethisterone may have effects similar to those attributed to oestrogens.
