Oral contraceptives: a risk factor for uncontrolled blood pressure among hypertensive women

The objective of the study was to assess the association between systolic and diastolic blood pressure (SBP and DBP) and the use of oral contraceptives (OC) in hypertensive women. In a prospective cross-sectional study, we evaluated 171 women who were referred to the Hypertension Outpatient Clinic of Hospital de Clínicas de Porto Alegre; 66 current users of OC, 26 users of other contraceptive methods and 79 women who were not using contraception. The average of six blood pressure readings was used to establish the usual blood pressure of the participants. Current OC users were compared with users of other methods and with patients not using contraception. Main outcome measures were SBP and DBP among the different groups, and prevalence of uncontrolled hypertension (SBP >or= 140 mmHg and DBP >or= 90 mmHg). DBP was higher in OC users (100.2 +/- 15.9 mmHg) than in patients using other contraceptive methods (93.4 +/- 14.7 mmHg) and not using contraceptives (93.3 +/- 14.4 mmHg, p = 0.016). Women using OC for more than 8 years presented higher age-adjusted blood pressure levels than women using OC for shorter periods. Patients using OC had poor blood pressure control (p for trend = 0.046) and a higher proportion of them presented moderate-severe hypertension. These results were independent of antihypertensive drug use. In a logistic regression model, we found that current OC use was independently and significantly associated with prevalence of uncontrolled hypertension. It is concluded that hypertensive women using OC present a significant increase in DBP and poor blood pressure control, independent of age, weight and antihypertensive drug treatment.