Calculating a newborn’s expected life span is one of the best ways to track a whole population’s health.

You don’t get that number with a crystal ball. You get it by finding out when people die and for what reason.

Worldwide, life expectancy has increased steadily over decades, thanks to advances in medicine, agriculture and technology that put most of the world’s countries on a positive track.

But something is happening in the United States that says we are on the wrong track.

For the third year in a row, a baby born this year is expected to live a shorter life than a child born a year earlier. And according to new research, that’s because working-age Americans, between the ages of 25 and 64, are dying at an alarming rate, bringing down a newborn’s expected life span.

A new study by Virginia Commonwealth University finds that this is a national problem that is particularly bad in certain areas. Maine, along with Vermont and New Hampshire, is experiencing some of the fastest increases in midlife death rates in the country.

Why? Because of increasing numbers of deaths resulting from suicide, drug overdoses, alcohol abuse and a range of diseases associated with obesity. It’s a cluster of conditions sometimes referred to as “deaths of despair”– deaths that would be preventable with appropriate public health interventions.

The study, which was published in the Journal of American Medical Association, breaks down the data by county, suggesting that there is an economic cause for these deaths.

The areas that have been hit the hardest by the “deaths of despair” are also the places that were hit the hardest by the Great Recession and have been the slowest to recover. For instance, Washington County had 931 deaths per 100,000 population in 2014, while in more prosperous Cumberland County, the rate was 726 per 100,000 – a 22 percent difference.

It’s important to remember that it doesn’t have to be this way.

Life expectancy is still increasing in the other countries in the developed world. People in European countries that are similar demographically to Maine are living longer and healthier lives. We have the same information that they have when it comes to nutrition and mental health care.

And it’s not because we can’t afford to keep people in good health. America spends more per capita on health care than any industrialized nation – twice as much as some countries.

Newborn American babies should not be facing ever-shorter life expectancies because we failed to act.

We can identify the trend. We know what’s causing it. It’s up to us to turn it around.