Hormone therapy is often discussed in terms of hot flashes, sleep, bone health and long-term disease risk. But a new study points to another reason menopause research can be difficult to interpret: Women who use hormone therapy may differ from nonusers in more ways than their hormone use.
In a large observational study published in Menopause, researchers analyzed data from more than 10,000 women to examine whether menopause status and hormone therapy use were associated with modifiable health behaviors, including diet, physical activity and sleep duration. The study found several lifestyle differences across groups, but it was not designed to prove that hormone therapy caused those differences.
That distinction matters because hormone therapy use may also reflect other factors, including symptom severity, access to care, socioeconomic resources, health literacy and how proactive someone is about seeking medical guidance.
“This large observational study underscores that women who use hormone therapy tend to adopt overall healthier lifestyles,” said Stephanie Faubion, MD, medical director for The Menopause Society. “Although this association may partly reflect better symptom control enabling healthier behaviors, healthy-user bias is likely a significant contributor.”
Healthy-user bias is a common challenge in observational health research. It means that people who use a treatment, supplement or preventive service may already differ from those who do not. They may have more regular contact with clinicians, more information, more resources or stronger health habits before the treatment is ever part of the picture.
In this study, postmenopausal women who had never used hormone therapy reported lower fruit and vegetable intake than some other groups. They were also 19% less likely to meet strength-based activity guidelines.
Sleep patterns were more complicated. Compared with premenopausal and perimenopausal women, the likelihood of meeting sleep guidelines was 14% lower among postmenopausal women who had never used hormone therapy, 26% lower among current hormone therapy users and 24% lower among past users.
Those findings do not tell a simple story in which hormone therapy users sleep better or have uniformly healthier routines. Instead, they suggest that menopause status and hormone therapy use are linked with different patterns of daily health behaviors, and those patterns may be shaped by multiple forces at once.
Menopause itself can affect sleep, body composition, cardiovascular risk and other aspects of health. Hot flashes, night sweats and urogenital symptoms can disrupt sleep, while hormonal changes may influence how women feel, move and recover. For some women, hormone therapy can help relieve certain menopause symptoms, which could make it easier to sleep, exercise or maintain daily routines. For others, hormone therapy use may be a marker of greater access to care rather than the driver of healthier habits.
Faubion said that issue has affected hormone therapy research before.
“Women who choose to use hormone therapy are often more proactive in their healthcare and may systematically differ from nonusers in socioeconomic resources, access to care, and health literacy,” she said. “This largely explains why early observational studies of hormone therapy suggested cardiovascular benefits that were not confirmed in subsequent randomized, controlled trials.”
The new study does not argue for or against hormone therapy. Decisions about hormone therapy are individualized and depend on symptoms, age, timing since menopause, personal and family health history and risk factors. The findings are more useful as a reminder that studies of menopause and health behaviors need to account for who is using hormone therapy and what else may be different about their lives.
The diet findings also should not be read as a judgment about individual women’s choices. Fruit and vegetable intake, physical activity and sleep are shaped by work schedules, caregiving, income, neighborhood access, stress, symptoms and medical history. During midlife, those pressures often overlap with hormonal changes and changing health risks.
The study adds nuance to a period of life that is often reduced to symptoms or treatment decisions. Menopause is not just a hormonal milestone. It is also a time when sleep, eating patterns, movement, medical care and chronic disease risk can intersect in ways that are hard to separate.
The research used data from the Canadian Longitudinal Study on Aging, which is funded by the Government of Canada through the Canadian Institutes of Health Research and the Canada Foundation for Innovation, along with several Canadian provinces. This study also received funding from a Canadian Institutes of Health Research Catalyst grant. Several authors reported professional roles related to nutrition, metabolism, healthy aging or exercise physiology.