Low-dose oral contraception and blood pressure in women with a past history of elevated blood pressure.

Sixty-one women with a past history of elevated blood pressure (high-risk group) associated with oral contraceptive use (27 patients), unknown etiology (17 patients), or preeclampsia (17 patients) used a low-dose oral contraceptive containing 0.4 mg of norethindrone and 35 micrograms of ethinyl estradiol for 3 to 24 months. The highest blood pressures recorded in the past were 141.0 +/- 14.9 (mean +/- SD) mm Hg systolic and 98.3 +/- 8.0 diastolic. Sixty-one women without a past history of elevated blood pressure (low-risk group), selected from a pool of 616 low-risk patients, were matched with the high-risk group for race, initial age, initial body weight, duration of use, history of smoking, and family history of hypertension. The blood pressures in the high-risk group before and after oral contraceptive therapy were significantly higher than those in the low-risk group. Despite these differences, the mean systolic and diastolic blood pressures in these two groups of women using the low-dose oral contraceptive did not rise when compared with their own baseline blood pressures. Five high-risk patients (8.2%) discontinued therapy because of the redevelopment of hypertension; however, blood pressures at discontinuance were comparable to the previous highest blood pressures.