For more than 30 years, the Women’s Health Initiative (WHI), a historic, federally funded research effort focused on women’s health, has led to landmark discoveries in areas such as hormone therapy, cancer, and cardiovascular disease. Now, though, the Trump administration is shutting down the project. On Tuesday, WHI scientists were notified that the federal contracts supporting all four regional centers—in Buffalo, New York; Winston-Salem, North Carolina; Columbus, Ohio; and Stanford, California—will be terminated in September 2025. The initiative’s clinical coordinating center in Seattle, which manages the data collection and analysis for all research under the WHI umbrella, will continue operating until January 2026. After that, its funding remains uncertain. The entire initiative’s current annual budget is less than $10 million.
It is hard to overstate the breadth and significance of the WHI’s research. The National Institutes of Health (NIH) launched the initiative to make up for a lack of understanding of the unique elements that contribute to women’s health—up to that point, most medical research had been conducted relying only on men as the subjects of study. In 1993, scientists at 40 clinical centers around the country began collecting detailed health data on more than 160,000 women, including their illnesses, diets, exercise habits, and medications they took. (Today, more than 42,000 women, aged 78 to 108, remain active in WHI research.)
One of those scientists was endocrinologist and epidemiologist JoAnn Manson, a WHI principal investigator who has been with the project since its inception and helped recruit participants to the initial studies. A professor at Harvard Medical School and the Harvard T.H. Chan School of Public Health, Manson is the chief of preventive medicine at Brigham and Women’s Hospital. “The disruption of the WHI program,” she says, “will lead to incalculable losses to scientific discovery and human health.”
Over the decades, the initiative has documented thousands of cancer cases, cardiovascular events, bone fractures, and deaths. Its findings have led to major changes in clinical guidelines and public health policies. Famously, after a WHI clinical trial revealed that menopausal hormone therapy combining estrogen and progestin significantly increased the risk of breast cancer and did not protect heart health, the findings dramatically shifted physicians’ prescribing practices. Initiative research also showed that, contrary to previous assumptions, taking vitamin D and calcium does not decrease the risk of osteoporosis and cancer.
“This is an extraordinarily productive and cost-efficient study,” Manson says. The hormone-therapy clinical trial alone is estimated to have saved $35 billion in direct medical costs, by improving clinicians’ decision-making. “It’s a treasure trove of knowledge and resources, and there’s so much more to be learned from it. To cut that short is really unfathomable.”
On Thursday, Harvard Magazine spoke with Manson about the WHI’s significance, her own work with the initiative, and what happens next. Some answers have been edited for clarity.
Can you tell us a little bit about the work you’ve been involved in as a principal investigator?
I’ve been very actively involved in the hormone-therapy trials in women with and without hysterectomies—they’re actually two separate trials—doing very detailed analysis of who benefited from hormone therapy and who did not. We were able to establish that the benefit-risk ratio varied according to age, time since menopause, and underlying health status of women. So, the answer is not one size fits all. Women in early menopause tended to do better on hormone therapy than the women more distant from menopause.
I was also really involved with all of the randomized trials of the WHI, particularly in the study of cardiovascular disease. I’ve also worked on studies of diabetes and of age-related memory loss and cognitive decline, studies of age-related chronic disease outcomes. And also: breast cancer. I’ve been studying healthy aging, how to prevent chronic diseases, how to extend the health span. And I’ve also been very involved with mentoring and training the next generation of researchers in the field.
It seems as though ending the WHI would harm older women especially.
There will be a devastating loss to women’s health, all post-menopausal women, and really a loss to the health of all older adults in the population, because the findings are relevant not only to women but to older adults in general. We are studying some of the leading causes of age-related chronic disease, and the WHI is really the largest, most groundbreaking study of these age-related chronic conditions.
It’s influencing medical and clinical guidelines in so many health conditions, especially in older adults. It is shedding light on so many forms of cardiovascular disease that have been minimally studied in the past, like heart failure and atrial fibrillation, in addition to heart attacks and strokes. It’s looking at how to reduce the risks of cognitive decline and mobility decline. This is so important to the quality of life of older adults. And the WHI has extensive geo-coding, to look at differences in risk by geographic areas in the country, rural versus urban. The whole initiative has this tremendous potential.
What was the intended timespan of the initiative when it was founded? Was it meant to collect data indefinitely?
Yes. Even though some of the participants have passed away, there are bloods that were collected at baseline and decades of follow-up and very detailed assessments, which will continue to provide tremendous insight into ways to prevent chronic disease. The study really could go on for many, many decades in terms of opportunities for scientific discovery.
Your specialty is preventive medicine. That’s been a major focus of the WHI, right?
Yes. And there’s an irony in that, because no study is a better example of the scientific impact of research on the prevention of chronic disease—and preventing chronic diseases is one of the stated priorities of the HHS [Department of Health and Human Services] leadership. The WHI has contributed so much in that area over the last 30-plus years, and it has the potential to yield major insights over coming decades. Answers are coming at a rapid pace, and to slash the funding of the largest and most groundbreaking study of women’s health and prevention of chronic disease is really shocking.
What’s next? What will happen now to the initiative’s repository of data?
It’s unclear what will happen after January 2026, when decisions are made about the clinical coordinating center. We’re certainly hoping that there will be some sustained funding to support research on the biomarkers, the bloods that have been collected. It was 160,000 women at baseline, and there have been multiple follow-up collections. It would really be just an extraordinary loss not to be able to oversee that resource. We are talking with each other within the WHI and planning out an appeal of the decision and next steps. So, everything’s in flux right now. This has been heartbreaking news.
