New research from Kaiser Permanente finds a link between high blood pressure — hypertension — and uterine fibroids in midlife women. The study suggests treating hypertension could play a role in preventing fibroids, a common condition for which no preventive treatment currently exists.

According to lead author Susanna Mitro, PhD, a research scientist with the Kaiser Permanente Division of Research (DOR), “This study confirms in a high-quality way that hypertension increases risk of fibroids.”

Understanding if there is a biological reason for this association could lead to new treatment options for fibroids.  “That would be a big step forward,” Dr. Mitro added.

Pain and fertility issues

Growths in the uterus, also known as uterine fibroids, affect about three-quarters of women by age 50. They can grow large and numerous, causing pain and fertility issues, among other problems that can lead to a hysterectomy. And yet, fibroids are not well understood.

The study was published in JAMA Network Open earlier this spring. Researchers analyzed data from 2,570 women between 42 and 52 in age who had not been previously diagnosed with uterine fibroids. These women participated in the Study of Women’s Health Across the Nation (SWAN), a multi-site study that has followed patients from enrollment in the mid-1990s through 13 semi-annual visits for more than 15 years.

SWAN researchers collected data about numerous health issues, including blood pressure, fibroid diagnoses, and treatment with any of 6 different hypertension medications. They found that patients taking one of them – ACE inhibitors – were 48% less likely than patients with untreated hypertension to have a new fibroid diagnosis.

“A strength of this study was following patients over many years rather than a snapshot in time,” said senior author Monique Hedderson, PhD, a senior research scientist at DOR and co-principal investigator of the SWAN cohort in which DOR participates.

Findings from the study include:

• Twenty percent of all participants reported a new fibroid diagnosis.
• Patients with a new hypertension diagnosis had a 45% greater risk of newly diagnosed fibroids, compared to those with no hypertension.
• Among the patients with hypertension, those being treated with anti-hypertensive medication had a 37% lower risk of newly diagnosed fibroids than those with untreated high blood pressure.

The researchers tracked other factors, including weight and blood biomarkers of cardiovascular disease risk, such as cholesterol. They found these other factors were not associated with fibroid risk.

Previous research has focused on the role hormones play in developing the fibroids. This study added to the evidence that there’s a connection between lower risk of fibroids and a non-hormonal factor, antihypertensive medication.

“We know so little about fibroids,” Mitro said. “Understanding different mechanisms that control fibroid growth or development has a lot of potential to change how people are treated.”

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