American women are facing poorer health prospects on several fronts these days.

The latest study, published today in JAMA, looked at national trends in obesity and found a disturbing rise among adult women over the most recent decade, from 2005 to 2014. Meanwhile, the authors found that obesity rates among men had plateaued.

By 2014, that meant that 40 percent of women were obese, while 35 percent of men were. For morbid obesity (a body mass index of 40 or greater), the rates for women compared with men were even more startling: 5.5 percent of men were morbidly obese, while 10 percent of women were — a rate that had been rising over time.

In the analysis, the JAMA researchers tried to drill down to see whether the changes among women were related to any overall changes in education, smoking status, race, or age among the female participants. "None of those things explained the increase we saw," said Cynthia Ogden, one of the four study authors, who all conduct research at the National Center for Health Statistics at the Centers for Disease Control and Prevention. They called for more studies to figure out the reason for the trend.

Brian Elbel, a professor in population health and health policy at the NYU School of Medicine, said the obesity-in-women puzzle underscores the fact that as a society, we simply haven't figured out how to address or combat obesity. "We're still seeing plateaus and increases in the obesity rates," he said, "and we don't know why the plateaus happened, or why the increases happened."

Researchers are similarly concerned by a number of other trends that are dramatically affecting the overall survival of women in the US.

The death rate among white middle-aged women is rising

Analyzing changes in the death rate among middle-aged white women, Columbia University statistician Andrew Gelman found that from 1999 to 2013, the death rate steadily increased, while for white men it has been decreasing since 2005.

In a separate article, researchers at the Urban Institute noted that the trend reflects what's going on with American women generally (not just non-Hispanic white women). The outlook is particularly dismal when they're compared with groups in other countries.

"There is simply no mistaking the reality that American women are currently dying much earlier than their counterparts in other advanced nations," the authors wrote.

They cited past studies documenting a similar rise in deaths among women. See, for instance, work by the National Academy of Sciences and the Institute of Medicine, which shows that "Americans are slipping behind other high-income countries when it comes to mortality and survival, and that this 'US health disadvantage' has been growing particularly among women."

And women of all ages seem to be affected. Analyzing county-level data within the US, researchers from the University of Wisconsin have found that female mortality rates have been increasing in recent years at a much higher rate than they have for men.

Again, no one can fully explain why this is happening. But the Urban Institute researchers point out that an uptick in accidental poisonings — linked to prescription painkillers and heroin use — is a problem. And that "obesity- and smoking-related diseases are driving these mortality increases."

The suicide gap between men and women is shrinking

Men have always had higher suicide rates than women — but the gap has been shrinking since the late 1990s with an uptick in suicides among women.

Between 1999 and 2014, there was a 45 percent increase in the suicide rate in women (whereas the rise among men was 16 percent during the same period).

Maternal mortality is on the way up

The likelihood of a women dying during childbirth has also risen significantly in the US, and American women are more likely to see this fate compared with those in any other developed country.

According to an analysis by the Economist, this may also be explained by the fact that "American women tend to be both fatter and older when they become pregnant these days." So rising obesity may also be increasing the risk of death among women in childbirth, they wrote:

… more women are in poorer health when they get pregnant, and then failing to get proper care. Chronic health problems, such as obesity, hypertension, diabetes and heart disease, are increasingly common among pregnant American women, and each of them makes delivery more dangerous.

Janet Currie, a Princeton health economist, cautioned that while some measures of poor health among Americans have been linked to a flagging economy, the obesity trends shouldn't be interpreted this way.

It typically takes years to become obese, she said. "Ten years ago, [the economy] was really great, yet you still saw this increase in obesity going on." Not to mention that American men fared worse than women during the Great Recession, yet their obesity didn’t increase over the past decade.

But not all women's health news is dismal

On several other health measures, American women are faring a lot better these days.

As Vox's Sarah Kliff reported, teen pregnancies reached a historic low in 2015, dropping by 43 percent since 2007 — and that's a big win for public health. That means more women will have a better chance at an education and stable income.

Relatedly, abortion rates have been plummeting for women in developed countries over the past three decades, while the use of contraceptives among US women has increased — all measures that indicate women are getting better at preventing unwanted pregnancies.

On several types of cancer, women have also seen gains. Cervical cancer screening has turned this uniformly deadly disease into a largely curable one.

Breast cancer prevention efforts have also led to some big health wins. Deaths from breast cancer have decreased significantly in recent years. In the period between 1975 and 2013, the breast cancer death rate dropped from 31 deaths in 100,000 to 21 deaths in 100,000 people.

A humble request: If you know of any worthwhile research explaining these trends among women, please send it my way.