If motherhood before marriage is the new norm for U.S. women under age 30, it’s urgent to find out why.

Politicians railing against the decline of family values won’t be much help. Evidence suggests that money rather than morality underlies this troubling trend. We need to find out the root causes to decide how to deal with it.

More than half of babies born to U.S. women younger than 30 occur outside marriage, according to a New York Times report.

But the trend is dramatically different based on education levels: 92 percent of women with college degrees are married when they have a baby, compared to 43 percent of those with a high school diploma or less.

The fastest growth was among young white women.

Babies born to single mothers are more likely to grow up in poverty, founder in school and have emotional or behavioral problems. If we don’t catch these problems before they start, society will pay a much higher economic and social cost down the road.

Most young women say they’d like to marry if they could find the right man. About eight in 10 unmarried new mothers say they hope to marry their children’s father some day, but fewer than one in seven has done so by the time their kids turn 3, according to sociologists Kathryn Edin and Maria Kefalas, authors of the book “Promises I Can Keep: Why Poor Women Put Motherhood Before Marriage.”

So what gets in the way?

The sexual revolution is a convenient whipping boy for political demagogues, who say the fact that young women don’t need men to support their babies has been the ruination of family values. If that were the case, college-educated women with higher incomes would be more likely to give birth without marrying than less educated women. And that’s not the picture.

Edin and Kefalas found that women in their 20s don’t want to rush into a wedding that’s likely to end in divorce. And when they take a good look at their babies’ fathers, they don’t always see Mr. Right.

The elephant in the room is the economic predicament of today’s young men who are not college-educated. They face a much trickier job market and unstable financial future than they used to. Entry-level wages for men who finish high school have fallen 23 percent since 1973, adjusted for inflation. Some of the sharpest drops in married two-parent families are in places such as Loraine, Ohio, since the steel mills closed.

Funny how lack of money and an uncertain future can change your point of view or others’ views of you.

Even if some guys want to do the right thing for their babies, they may be reluctant to make a lifelong commitment to the mothers when they don’t know where they’ll get their next paycheck. And young women who want to have babies may dodge marriage for similar reasons.

It’s tempting to wish we could turn back the clock to the 1950s and make married-with-children the norm. But the ‘50s weren’t paradise either, especially for women trapped in unhappy marriages.

Instead, we need to find ways to improve the economic status of young men to make marriage a more attractive and realistic option.

And we need to deal with a new generation of kids likely to need more help with school and job skills.

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