Oral contraceptives and hypertension in women: results of the enrolment phase of Tabari Cohort Study

Background The association between oral contraceptives (OCP) and hypertension has been reported in the literature with controversial results. According to the growing use of OCPs among women in Iran, this study aims to investigate the association between the duration of the OCP consumption and risk of hypertension among Iranian women. Methods In the current study, the data collected during the enrolment phase of the Tabari cohort were analyzed. Of 6106 women recruited in the cohort, 133 pregnant women were excluded. Epidemiological variables were collected using pre-designed questionnaires as well as the health insurance evidences. In addition, blood pressure and anthropometric factors were measured based on the standard guidelines. Chi square and partial correlation tests as well as logistic regression models were applied for data analysis. Results Frequency of oral contraceptive use among 35-70 year-old women in Tabari cohort study (TCS) was 42.2% (2520/5973). Hypertension was observed among 25% (1793/5973) of them. The adjusted odds ratio for OCP use was 1.23 (95% confidence interval: 1.08, 1.40, p = 0.002). The corresponding odds ratios for 61-120 months and more than 120 months OCP use were 1.39 (1.12,1.73) and 1.47 (1.16,1.87) respectively. Conclusions Oral contraceptives especially in long term use can be associated with hypertension.