The economy is in robust good health, but our social fabric isn’t.

By two basic measures of ­social vitality, births and deaths, American society is faltering. Both the fertility rate and life expectancy are declining, in a sign that people feel less secure and, in some cases, have no hope at all.

We are attuned to headline-grabbing economic statistics — GDP growth, the unemployment rate, wages — as monthly and quarterly metrics of American well-being, but they aren’t as telling as these more fundamental indicators.

To put it bluntly, contemporary America is characterized by less procreation and more self-destruction. This suggests that something is profoundly wrong with the state of the union, although it doesn’t ­receive the attention and the debate it deserves.

The fertility rate in 2018 dropped for the fourth straight year. It has hit a record low and has fallen 15 percent since 2007. With the ­recovery after the Great Recession, the rate bumped up a little in 2014 before receding again.

If America is still doing better than other advanced counties, where fertility has also been declining, it may yet fall further still.

Part of the story is a steep drop over the years in teenage pregnancy, a welcome and long-sought development. Women in their 20s have also been having fewer children, though. The trend is toward women delaying having children and having fewer of them.

As demographer Lyman Stone points out, the fertility rate for married women has basically held up over the past decade, even as the overall fertility rate has declined. This is because the share of women who are married has been falling.

The survey data tend to show that women still want kids, he notes, in fact perhaps more children than before. But later-in-life childbearing is inherently more difficult, and student debt, high housing costs and intense parental investment in children make having kids more burdensome (or at least to feel that way).

While we now have fewer births, the death rate is increasing. A new study published in the Journal of the American Medical Association notes that after stalling out in 2010, life expectancy in the country has been declining since 2014, down to 78.6 in 2017 from 78.9 years.

The United States has been losing ground to other nations in life expectancy since the 1980s. According to the Kaiser Family Foundation, it now has the lowest life expectancy among comparable states.

The decline isn’t hitting older Americans, who are still making improvements, but is cutting down people in the prime of their lives, ages 25-64. “The odds,” Lyman Stone writes, “that a 32-year-old will die in a given year rose by almost 25 percent between 2012-14 and 2015-17. American adulthood has suddenly become more lethal than it has been in decades.”

Drug overdoses are a major driver (midlife mortality from drug overdoses has increased ­almost 400 percent over the past 20 years), with liver disease and suicide also contributing.

In 2017, an astonishing 150,000 Americans died from drug or alcohol abuse and suicide, more than US combat deaths in World War I, the Korean War and the Vietnam War combined.

Evidence suggests that the increased mortality is concentrated among the working class. According to the JAMA study, “the gradient in life expectancy based on income has . . . widened over time, with outcomes at the lower end of the distribution explaining much of the US disadvantage relative to other countries.”

If we can get a handle on the opioid crisis, it will make an enormous difference, but the trends in life expectancy and fertility ought to occasion soul-searching. How is it that a society as technologically advanced and affluent as ours can’t provide a more inviting environment for childbearing or the supports to keep people from doing themselves grievous harm?

Even if there are no ready policy answers, the question must be asked.

Twitter: @RichLowry