When young couples of the ’60s and ’70s thought about the future, their path forward was often clear: get married, move in, have babies. Two of the steps of that sequence swapped places decades ago—for the first time, in the mid-’90s, over half of all couples lived together before marriage. Now, researchers are finding that the order is again undergoing change: More and more Americans are first sharing a home, then having children. Marriage comes later, if at all.

A report published today by the Pew Research Center finds that 35 percent of all unmarried parents are now living together, up from 20 percent of unmarried parents in 1997. In 1968, the first time the government recorded data on this trend, less than 1 percent of unmarried parents cohabited. While the Pew study defines “cohabiting couples” as including either one or both of the child’s parents—meaning, a couple could be a parent plus his or her new partner—scholars I spoke with told me this trend is driven by an uptick in families in which both members of the couple are also the parents. (The report doesn’t specify how the data breaks down among gay and straight couples.)

More parents are likely choosing to live together without marrying because of the economy, said Arielle Kuperberg, a sociology professor who specializes in cohabitation at the University of North Carolina at Greensboro. Cohabiting parents, according to the Pew study, are significantly younger and less educated than both single parents and married parents. Many Millennials who came of age during or soon after the Great Recession are still struggling to find financial security. Even though they’re making, on average, more money than Millennials a few years ago, their net worth is still low, compared to past generations, largely because of their debt. “That’s just not the kind of stability that people want to have before they start making legal ties to each other,” said Kuperberg.   

For many young couples, financial stability is a sort of prerequisite for marriage. “Particularly if your partner doesn’t have good financial practices, or has a lot of debt, or a bad credit score, combining your finances with that person might hurt your chances of being financially stable yourself,” said Kuperberg, who is currently researching how debts and loans affect relationships. Young people saddled with large amounts of student debt, she said, are often hesitant to marry. If one partner participates in an income-based student-loan program, then marries and files a joint tax return, the government will consider the spouse’s income, and increase the loan payment. While marriage does afford couples some financial benefits, they can take advantage of most of them—sharing the rent, utility bills, and furniture—just by living together. Many other financial benefits of marriage, like Social Security and inheritance rights, don’t typically materialize until later in life.

Due in part to the search for an elusive degree of financial stability, Americans today are marrying later in life, as the sociologist Andrew Cherlin wrote in a recent essay for The Atlantic. But that doesn’t mean they delay having kids. In her book, Promises I Can Keep, the sociologist Kathryn Edin recounts conversations with dozens of low-income women who choose to have kids before they get married. The women featured in the book don’t want to legally attach themselves to someone who doesn’t have a steady job, or someone with a ton of debt—but they do want children. If the woman has a partner, but still isn’t sure he’s the one she wants to marry, raising their child together as cohabiting partners might seem like a good option.

There has been an accompanying shift in values around marriage and childbearing. While having kids “out of wedlock” used to be a serious taboo, today, 74 percent of people say it’s okay to have children while you’re cohabiting. “There is no negative norm against it, it’s accepted,” said Wendy Manning, the director of the Center for Family and Demographic Research at Bowling Green State University. “My question isn’t ‘Why have children as an unmarried, cohabiting couple?,’ but ‘Why not?’” “Shotgun weddings,” Manning told me, are quickly being replaced by “shotgun cohabitations”—in response to an unintended pregnancy, a couple is three times more likely to move in together than get married.  

After conducting a series of interviews with cohabiting parents, Manning found that many were just as committed to their families as their married peers. “They’re making a lifelong commitment to their child by living together and raising their children in a two-parent family,” said Manning. “They don’t feel that marriage is important—it’s more important that they are there, every day, taking care of their kids.”

Not everyone is so sure this trend is a good thing. Cohabiting unions, however well-intentioned, are still far less stable than marriages. They lack what Kuperberg calls the “external barriers”—legal fees, formal paperwork, court processes—that stand between marriage and divorce. Compared to kids born into marriage, kids born to cohabiting parents are less likely to continue to live with both parents as they grow up. On the other hand, the divorce rate is down, which, according to Kuperberg, signals that people who may have once rushed into marriage are instead choosing to cohabit.

In a certain sense, it looks like relationships in the U.S. are evolving as they have in several Nordic countries over the past few decades. “In Sweden, for example, it’s now so common for parents to have kids in cohabiting unions that, over time, more and more rights have been given to cohabiting couples,” said Kuperberg. “Marriage and living together have become legally indistinguishable.” But it’s not quite the same: With adults who are among the wealthiest in the world, the Nordic pattern is slightly different.

It’s clear that American families are changing, at least somewhat. Then again, maybe families with cohabiting parents aren’t all that different. “This is the two-biological-parent family that everyone has been talking about forever,” Manning said. In many ways, she told me, it’s the familial “gold standard.” It just might take some time for everyone to see it that way.