The most significant finding is perhaps that non-oral estradiol (a specific form of estrogen) at the lowest dose and for the shortest period of time was associated with the lowest risk of developing high blood pressure.
Oral estrogen was also associated with the following increase in high blood pressure risk compared to non-oral options:
- 14% higher risk of high blood pressure compared to transdermal cream
- 19% greater risk of high blood pressure compared to vaginal estrogen creams or suppositories
Taking estrogen for a longer period of time or taking a higher dose was also associated with a greater risk of high blood pressure.
The study authors say these findings suggest there are different types of estrogen that may have lower cardiovascular risks from women using estrogen for hormone replacement therapy during menopause.
The study was funded by the Canadian Institutes of Health Research.
Estrogen hormone therapy is also used in gender-affirming care and in contraception, so the impact of this research may extend beyond the menopause life stage. But what is it about estrogen that impacts blood pressure?
Experts say the link comes down to its effects on vessels.
Dr. Jennifer Bourgeois, PharmD, IHP, FAIS, a pharmacy and health expert at SingleCare says that while it’s well established that estrogen has a cardioprotective effect regarding vascular inflammation, the role of estrogen in hypertension or high blood pressure is still debatable.
“This new research proves there is more to the story regarding oral synthetic estrogen being linked to hypertension,” she tells Healthline.
These findings are also in line with previous evidence. Dr. Zahra Ameen, BSc, MBBS, MRCOG, a consultant gynecologist and obstetrician at the Cadogan Clinic in London, England tells Healthline it’s generally accepted that non-oral hormone replacement therapy (HRT) preparations, and in particular transdermal estrogen, are safer forms of HRT, with a lower risk of venous thromboembolism (blood clots). Examples of transdermal estrogen include EstroGel or Evorel / Estradot patches.
Dr. Ameen points to a systematic review published in the 2023
“Transdermal HRT preparations are as effective as oral preparations in treating HRT symptoms,” says Ameen to Healthline. Not only that, but she says a lower dose of a transdermal preparation will have an equivalent effect and benefit on symptoms as an oral preparation.
“This is because oral oestrogens are first metabolized by the liver before entering a person’s systemic circulation, whereas transdermal estrogen avoids metabolism in the liver (first pass metabolism) and therefore can be given in lower doses for equivalent effects,” explains Ameen.
It’s also known that estrogen prescribed as a gel or a patch will have the effect of widening the blood vessels, which can help to lower blood pressure, says Ameen.
The study authors note limitations which include only reviewing data from women over 45 years and only looking at data from women on estrogen-only therapy.
Ameen says this is the main limitation of the study, and suggests more research is needed.
“It only looked at women who were taking estrogen-only HRT (i.e women who have had a previous hysterectomy or surgical removal of the uterus) and not women on combined HRT preparations (containing estrogen and progesterone),” she notes.
“In fact, micronized progesterone currently commonly used, seems to have no effect on BP and can even help to lower it,” she says.
When starting a woman on HRT, Ameen says it’s very important to assess the overall picture as risks to blood pressure will vary on an individual basis depending on age, general health, weight, smoking status, presence of an intact womb, as well as the type of HRT.
“It is also important to weigh up the risk/benefit analysis for women in terms of their risks of taking HRT versus the significant improvement in quality of life that they may experience from taking HRT,” says Ameen.
“The best tip to combat high blood pressure during menopause is to maintain a healthy lifestyle,” says Bourgeois.
Bourgeois says following a healthier lifestyle can include:
Ameen echoes this and highlights that all women, regardless of whether they are taking HRT or not, should aim during/after menopause to eat well, exercise regularly, not smoke, and maintain a healthy body weight.
These recommendations are due to the fact that regardless of whether a woman is taking HRT, Ameen says once she goes through menopause her risks of stroke, raised BP, and cardiovascular disease will increase.
Managing those risks then comes down to managing these lifestyle factors.