Women make up more than 50% of the population, yet before the 1990s they were largely excluded from health and medical research studies.

To try to help correct this imbalance, in 1991 the National Institutes of Health launched a massive, long-term study called the Women’s Health Initiative, which is still running today. It is the largest, longest and most comprehensive study on women’s health ever conducted in the U.S. It also is one of the most productive studies in history, with more than 2,400 published scientific papers in leading medical journals.

On April 20, 2025, the Department of Health and Human Services told the study’s lead investigators it plans to terminate much of the program’s funding and discontinue its regional center contracts. On April 24, after pushback from the medical community, HHS officials said the funding had been reinstated. But the reversal was never officially confirmed, so the study’s lead investigators – including me – remain concerned about its future.

I am a public health researcher who has studied chronic disease prevention in women for nearly 40 years. I have been centrally involved with the Women’s Health Initiative since its inception and currently co-direct one of its four regional centers at the University at Buffalo.

The project’s findings have shaped clinical practice, prevention strategies and public health policies across the U.S. and the world, particularly for older women. In my view, its loss would be a devastating blow to women’s health.

An imperative to invest in women’s health

The Women’s Health Initiative was established in response to a growing realization that very little medical research existed to inform health care that was specifically relevant to women. In the U.S. in the 1970s, for example, almost 40% of postmenopausal women were taking estrogen, but no large clinical trials had studied the risks and benefits. In 1985 an NIH task force outlined the need for long-term research on women’s health.

Launched by Bernadine Healy, the first woman to serve as director of the NIH, the Women’s Health Initiative aimed to study ways to prevent heart disease, cancer and osteoporosis.

Between 1993 and 1998, the project enrolled 161,808 postmenopausal women ages 50 to 79 to participate in four randomized clinical trials. Two of them investigated how menopausal hormone therapy affects the risk of heart disease, breast cancer, hip fractures and cognition. Another examined the effects of a low-fat, high-fiber diet on breast and colorectal cancers as well as heart disease. The fourth looked at whether taking calcium plus vitamin D supplements helps prevent hip fractures and colorectal cancer.

Women could participate in just one or in multiple trials. More than 90,000 also took part in a long-term observational study that used medical records and surveys to probe the link between risk factors and disease outcomes over time.

Clarifying the effects of hormone therapy

Some of the most important findings from the Women’s Health Initiative addressed the effects of menopausal hormone therapy.

The hormone therapy trial testing a combination of estrogen and progesterone was set to run until 2005. However, it was terminated early, in 2002, when results showed an increased risk in heart disease, stroke, blood clotting disorders and breast cancer, as well as cognitive decline and dementia. The trial of estrogen alone also raised safety concerns, though both types of therapy reduced the risk of bone fractures.

After these findings were reported, menopausal hormone therapy prescriptions dropped sharply in the U.S. and worldwide. One study estimated that the decreased use of estrogen and progesterone therapy between 2002 and 2012 prevented as many as 126,000 breast cancer cases and 76,000 cardiovascular disease cases – and saved the U.S. an estimated US$35 billion in direct medical costs.

Reanalyses of data from these studies over the past decade have provided a more nuanced clinical picture for safely using menopausal hormone therapy. They showed that the timing of treatment matters, and that when taken before age 60 or within 10 years of menopause, hormones have more limited risk.

Defining clinical practice

Although the Women’s Health Initiative’s four original clinical trials ended by 2005, researchers have continued to follow participants, collect new data and launch spinoff studies that shape health recommendations for women over 65.

Almost a decade ago, for example, research at my institution and others found in a study of 6,500 women ages 63 to 99 that just 30 minutes of low to moderate physical activity was enough to significantly boost their health. The study led to changes in national public health guidelines. Subsequent studies are continuing to explore how physical activity affects aging and whether being less sedentary can protect women against heart disease.

Bone health and preventing fractures have also been a major focus of the Women’s Health Initiative, with research helping to establish guidelines for osteoporosis screening and investigating the link between dietary protein intake and bone health.

One of the Women’s Health Initiative’s biggest yields is its vast repository of health data collected annually from tens of thousands of women over more than 30 years. The data consists of survey responses on topics such as diet, physical activity and family history; information on major health outcomes such as heart disease, diabetes, cancer and cause of death, verified using medical records; and a trove of biological samples, including 5 million blood vials and genetic information from 50,000 participants.

Any researcher can access this repository to explore associations between blood biomarkers, disease outcomes, genes, lifestyle factors and other health features. More than 300 such studies are investigating health outcomes related to stroke, cancer, diabetes, eye diseases, mental health, physical frailty and more. Thirty are currently running.

What does the future hold?

In addition to data amassed by the Women’s Health Initiative until now, about 42,000 participants from all 50 states, now ages 78 to 108, are still actively contributing to the study. This cohort is a rare treasure: Very few studies have collected such detailed, long-term information on a broad group of women of this age. Meanwhile, the demographic of older women is growing quickly.

Continuing to shed light on aging, disease risk and prevention in this population is vital. The questions guiding the project’s ongoing and planned research directly address the chronic diseases that Health Secretary Robert F. Kennedy Jr. has announced as national priorities.

So I hope that the Women’s Health Initiative can continue to generate discoveries that support women’s health well into the future.

Jean Wactawski-Wende, Professor of Public Health and Health Professions, University at Buffalo

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The problem with climate change isn’t just the temperature – it’s also how fast the climate is changing today.

Historically, Earth’s climate changes have generally happened over thousands to millions of years. Today, global temperatures are increasing by about 0.36 degrees Fahrenheit (0.2 degrees Celsius) per decade.

Imagine a car speeding up. Over time, human activities such as burning fossil fuels have increased the amount of greenhouse gases in the atmosphere. These gases trap heat from the Sun. This is like pressing the gas pedal. The faster the driver adds gas, the faster the car goes.

The 21st century has seen a dramatic acceleration in the rate of climate change, with global temperatures rising more than three times faster than in the previous century.

The faster pace and higher temperatures are changing habitat ranges for plants and animals. In some regions, the pace of change is also throwing off the delicate timing of pollination, putting plants and pollinators such as bees at risk.

Some species are already migrating

Most plant and animal species can tolerate or at least recover from short-term changes in climate, such as a heat wave. When the changes last longer, however, organisms may need to migrate into new areas to adapt for survival.

Some species are already moving toward higher latitudes and altitudes with cooler temperatures, altering their geographic territory to stay within their optimal climate. Fish populations, for example, have shifted toward the poles as ocean temperatures have risen.

Pollinators such as bees can also shift their ranges.

Bumblebees, for example, are adapted for cooler regions because of their fuzzy bodies. Some bumblebee populations have been disappearing from the southern parts of their geographic range and have been found in cooler regions to the north and in more mountainous areas. That could increase competition with existing bumblebee populations.

Plants and pollinators can get out of sync

Plants and their pollinators face another problem as the rate of climate change increases: Many plants rely on insects and other animals for seed and pollen dispersal.

Much of that pollen dispersal is accomplished by native pollinators. About 75% of plant species in North America require an insect pollinator – bees, butterflies, moths, flies, beetles, wasps, birds and bats. In fact, 1 in 3 bites of food you eat depend on a pollinator, according to the U.S. Department of Agriculture.

So, even if a species successfully migrates into a new territory, it can face a mismatch of pollination timing. This is known as phenological mismatch.

During the winter, insects go into a hibernation known as diapause, migrate or take up shelter underground, under rocks or in leaf litter. These insect pollinators use temperature and daylight length as cues for when to emerge or when to migrate to their spring and summer habitats.

As the rate of climate change increases, the chances of a timing mismatch between pollinators and the plants they pollinate rise.

With an increase in temperature, many plants are blooming earlier in the spring. If bees or other pollinators emerge at their “normal” time, flowers may already be blooming, reducing their chance for pollination.

If pollinators emerge too early, they may struggle to survive if their normal food sources are not yet available. Native bees, for example, rely on pollen for much of the protein they need for growing and thriving.

Wild bees are emerging earlier

This kind of shift in timing is already happening with bees in the U.S.

Studies have shown that the date wild bees emerge in the U.S. has shifted by 10.4 days earlier over the past 130 years, and the pace is accelerating.

One study found wild bees across species have been changing their phenology, or timing of seasonal activities, and over the past 50 years the emergence date is four times faster. That means wild bees were emerging roughly eight days earlier in 2020 than they did in 1970.

This trend of earlier emergence is generally consistent across organisms with the accelerating rate of climate change. If the timing mismatches continue to worsen, it could exacerbate the decline of pollinator populations and result in inadequate pollination for plants that rely on them.

Pollinator decline and inadequate pollination already account for a 3% to 5% decline in global fruit, vegetable, spice and nut production annually, a recent study found.

Without pollinators, ecosystems are less resilient − they are unable to absorb disturbances such as wildfires, adapt to changes, and recover from environmental stressors such as pollution, drought or floods.

Managing climate change

Pollinators face many other risks from human activities, including habitat loss from development and harm from pesticide use. Climate change adds to that list.

Taking steps to reduce the activities driving global warming can help keep these species thriving and carrying out their roles in nature into the future.

Courtney McGinnis, Professor of Biology, Medical Sciences and Environmental Sciences, Quinnipiac University

This article is republished from The Conversation under a Creative Commons license. Read the original article.