NATUROPATHIC DOCTOR IN ONTARIO
A Brief History of Menopausal Hormone Therapy
From Pregnant Mares to the Boardroom, MHT's Journey in North America
Hormone Therapy in Society
If you’ve ever wondered why hormone therapy carries so much cultural baggage — why your mother’s generation was told to avoid it, while today’s Menopause Society calls it the most effective treatment we have for hot flashes — the answer lies in an eighty-year history full of good science, bad incentives, one very influential book, and a study that changed medicine overnight. Here’s the short version.
Need help improving your health in perimenopause and menopause?
1942: A Drug Named After Horse Urine
Modern hormone therapy began in 1942, when the FDA approved Premarin — a name derived from its source: PREgnant MARe urINe. Formulated from estrogen extracted from the urine of pregnant horses, it was approved as a “replacement” therapy for a woman’s declining estrogen levels. It was effective, it was new, and for its first two decades, it was used relatively modestly.
1966: The Book that Changed Everything
That changed with a single book. In 1966, gynecologist Dr. Robert Wilson published Feminine Forever, arguing that menopause wasn’t a natural life stage but a “hormone deficiency disease” — one that could, and should, be treated with estrogen from puberty to the grave. The book was a bestseller, syndicated in Newsweek and Time, and it worked: within a decade, Premarin became the fifth most-prescribed drug in America. What wasn’t disclosed at the time was that Wilson’s research and foundation were quietly funded by Premarin’s manufacturer.
The 1970s Correction: Enter Progesterone
By the early 1970s, doctors noticed a troubling pattern: women taking estrogen alone, with a uterus still intact, were developing endometrial cancer at elevated rates. The fix, once understood, was straightforward — pairing estrogen with a progestin to protect the uterine lining. Combined hormone therapy was born, and by 1992, Premarin (now often prescribed alongside a progestin) had climbed back to become the single most-prescribed drug in the United States.
2002: The Study that Stopped the Industry Cold
Then came the Women’s Health Initiative (WHI) — a massive U.S. government trial designed to finally answer, with rigorous data, whether hormone therapy protected postmenopausal women from heart disease, fractures, and cancer. In 2002, the combined-therapy arm of the study was halted early. The early data suggested an increased risk of breast cancer, heart disease, stroke, and blood clots.
The headlines were immediate and brutal. Hormone therapy use collapsed by more than half within a year, and an entire generation of women — and their doctors — came away believing hormone therapy was simply dangerous.
The Two Decades that Followed: Putting the Data in Context
What wasn’t in the headlines was more complicated. As researchers went back and re-analyzed the WHI data over the following twenty years, a more nuanced picture emerged:
- The average WHI participant was 63 years old — many more than a decade past menopause — not the 50-year-old just starting to experience hot flashes that most hormone therapy patients actually are.
- The trial studied one specific formulation: oral conjugated equine estrogen with a synthetic progestin. It didn’t test transdermal estrogen or micronized progesterone, which we now understand carry a different risk profile.
- Risk, it turned out, depended heavily on when therapy started relative to menopause — what’s now called the “timing hypothesis.” Starting before age 60, or within about 10 years of menopause, showed a meaningfully more favorable balance of benefit and risk than starting later in life.
This more careful understanding built steadily through professional guidance over the following two decades, culminating in the Menopause Society’s 2022 position statement reaffirming hormone therapy’s role for appropriate candidates.
November 2025: The Symbolic Close of a Chapter
In November 2025, the FDA formally announced it would remove the boxed (“black box”) warning — the same stark cardiovascular disease, breast cancer, and dementia warning language that had sat on every estrogen product’s label since shortly after the WHI results broke — reflecting this more current, individualized understanding of risk. The warning about endometrial cancer risk in women taking estrogen without a progestin remains, since that risk is well-established and unchanged.
It’s a fitting bookend: the same federal agency that helped codify the fear born from 2002 spent the next two decades watching the science mature, and eventually said so publicly.
Menopausal Hormone Therapy Risks and Benefits, in Summary
None of this history means hormone therapy is risk-free — it means the risk-benefit picture is more specific to the individual than the 2002 headlines suggested. Broadly, here’s where the evidence stands today:
Benefits
- The most effective available treatment for hot flashes, night sweats, and vaginal/urogenital menopausal symptoms
- Protection against bone loss and reduced fracture risk
- Possible cardiovascular benefit when started within the “window of opportunity” (before 60, or within 10 years of menopause)
- Meaningful improvement in sleep, mood, joint pain, and quality of life for many women
Short-term risks / side effects
- Usually mild and transient: breast tenderness, bloating, mood changes, headaches, and irregular spotting in the first few months
- Typically resolves or improves with a dose, formulation, or route adjustment
Longer-term risks
- A small increase in breast cancer risk with combined estrogen-progestogen therapy after several years of use (estrogen-only therapy has not shown the same pattern)
- Higher risk of blood clots and stroke with oral estrogen specifically — transdermal routes (patch, gel) carry meaningfully lower risk
- Risk of endometrial cancer with unopposed estrogen in women with a uterus — effectively eliminated by taking progesterone as prescribed
- Cardiovascular risk that depends heavily on age and timing of initiation, underscoring why individualized assessment matters more than a blanket label ever could
Is Menopausal Hormone Therapy Safe?
The story of hormone therapy is, in many ways, the story of medicine learning to ask a better question — not “is this treatment safe?” but “safe for whom, at what age, in what form, and starting when?” That’s exactly the kind of individualized assessment we walk through with every patient.
This article is for general education and isn’t a substitute for an individualized conversation with your ND about your own health history and risk factors.
Dr. Sarah Goulding, Naturopathic Doctor
Dr. Sarah Goulding is a licensed naturopathic doctor in Ottawa Ontario and has a BSc in neuroscience and biology from Dalhousie University (2004), and did her 4-year naturopathic training at the Canadian College of Naturopathic Medicine (2010). She’s since accumulated over a decade of clinical experience, and refined her practice to focus on women’s health and digestion. She is licensed and registered as a Naturopathic Doctor in Ontario by The College of Naturopaths of Ontario (CONO) and is a member of the Canadian Association of Naturopathic Doctors (CAND) and the Ontario Association of Naturopathic Doctors (OAND).
Dr. Sarah Goulding blends science and compassion, and acts as a personal health researcher to help you navigate your health. Tools that she uses include nutrition, supplements and botanicals, bioidentical hormones, and lifestyle modifications. The closer you get to the root cause, the gentler the therapies needed to resolve the issue.
Dr. Janna Fung, Naturopathic Doctor
Dr. Janna Fung is a licensed naturopathic doctor with a special interest in dermatology and women’s health. She has a passion for evidence based preventative medicine and strives to empower patients with the knowledge to achieve their optimal health. She understands collaborations is the only way to develop realistic sustainable health/wellness results and strives to develop individualized health goals with patients.
