Researchers at the University of Wisconsin found an increasing female mortality rate at a national level in a study one researcher called the first of its kind.

Erika Cheng, co-author of the study, said she and her research partner David Kindig looked at premature mortality rates. She said premature mortality is defined as death before the age of 75.

Cheng said she and Kindig expected people, on average, would improve in regard to premature mortality. However, she said she was surprised to see an increasing female mortality rate at 43 percent of counties. She said they looked at rates over a 10-year period.

According to a UW statement, the study showed a trend of increasing female mortality rates in 42.8 percent of countries, a rate that is much higher than the 3.4 percent of male mortality Cheng and Kindig found over the same time period.

“[We are] looking at a more granular level,” Cheng said. “This research is emerging and people are more interested to see how this is doing over time.”

This research is innovative, according to Cheng, as she and Kindig were the first to look at changing mortality rates. She said looking at how counties have been doing over time is not something that has been done before, because people are more accustomed to looking at a national level.

Cheng said she and Kindig looked at many different factors associated with changes. They found the significant factors to be socioeconomic, and she cited education, income and poverty, population density and smoking as examples.

“Socioeconomic and behavioral factors are underappreciated for their effects on health, but with data like this, we see that those factors are important again and again,” Kindig said in the statement.

When these factors were controlled, Cheng said she and Kindig found counties in the west and the south have worse rates relative to the northeast. The statement said access to primary care physicians had no impact on their findings.

Cheng said she and Kindig hope people will use this study in a positive way to improve the health of their communities.

Funding for the study, Cheng said, came from the Robert Wood Johnson Foundation.

“There is not just one policy to make these things better,” Cheng said. “It’s going to be a balance.”