As women age, systolic blood pressure increases until eventually it is higher than that of men of a similar age. This postmenopausal increase in blood pressure has been attributed to estrogen deficiency. Studies looking at the effect of hormone replacement therapy (HRT) on blood pressure have not demonstrated consistent results. Scuteri and associates looked at the effect of HRT on the longitudinal increase in blood pressure that is associated with postmenopausal women using data from the Baltimore Longitudinal Study on Aging (BLSA).

Healthy postmenopausal women who consistently used oral or transdermal estrogen and progestin (HRT users) were compared with those who did not use them (HRT nonusers). Body mass index (BMI), lipid status, smoking history, alcohol use, and physical activity levels were determined.

Of the 226 postmenopausal women included in the analysis, 149 were HRT nonusers, and 77 were users. All other factors were similar in both groups. After a mean follow-up of 5.7 years, no statistically significant difference was seen in the average change in diastolic pressure, but the HRT nonusers had a significant increase in systolic blood pressure while the users did not. Further analysis revealed that the difference in systolic blood pressure between the two groups was accentuated in the older women and in women with a higher BMI. Diastolic pressure did not change significantly in either group.

The authors conclude that increases in systolic blood pressure in postmenopausal women are lower in those using HRT. This effect was more evident in older women and those with a higher BMI. HRT did not affect the diastolic blood pressure. Further studies are needed to confirm these observations.