Blood pressure changes and oral contraceptive use: a study of 2676 black women in the southeastern United States.

Blood pressure (BP) and weight were measured on 2676 black women attending a large southeastern family planning clinic. Repeat measurements were made after a minimum of six and upt to 24 months on 673 women who continuously used nonhormonal contraceptive (OC) therapy, and 1390 women who continuously used OCs. The mean change in systolic blood pressure (SBP) adjusted for initial BP and change in per cent ideal body weight is +1.44 mmHg in the new users of OC. This slight increase in SBP is statistically significant (p = 0.04) relative to the +0.41 mmHg increase observed in the control group. However, the adjusted diastolic blood pressure (DBP) change (+0.46 mmHg in new OC users and +1.54 mmHg in the control group) fails to support the hypothesis of a greater increase in DBP in new OC users. The adjusted mean rise in mean arterial BP does not differ significantly between new OC users and the control group. The proportion of women developing a DBP greater than or equal to 90 mmHg during the average follow-up interval of one year is 2.4% in the control group, 1.0% in the new OC users and 0.2% in the continued OC users. These results provide evidence that OC use has no significant effect on the level of mean arterial BP in black women followed for 6-24 months; and fail to support the hypothesis of a causal relationship between OC use and elevated BP in black women.