Effect of four combined oral contraceptives on blood pressure in the pill-free interval

Objective-To evaluate blood pressure changes in the pill-free interval and from baseline among women taking four different low-dose monophasic oral contraceptives. Design-131 women were randomized to four different oral contraceptives. Pressures were obtained at baseline, at the end of treatment cycles and at the end of the 7 pill-free days, during 6 months of treatment. Pressures were obtained at 4 and 8 weeks after discontinuation. Group 1 received norethisterone acetate 1000 μg, group 2 received levonorgestrel 150 μg, group 3 received desogestrel 150 μg, and group 4 received gestodene 75 μg, all combined with ethinyloestradiol 30μg. Results-All four groups showed an increase in pressure during treatment, with return to baseline levels four weeks after treatment. At the end of the pill-free interval, the readings did not differ significantly from on treatment except for women in Group 4, who experienced an increase in diastolic pressure. Conclusions-Use of the four oral contraceptives was associated with a small increase in systolic and diastolic pressure. Whatever mechanism causes the increase is not entirely reversible by 7 days without treatment.