From the United States to the United Kingdom, from Peru to the Philippines, marriage is in retreat and cohabitation is on the advance. The implications of this shift for adults are much debated; some see it as an important indicator of liberation, others see it as a troubling sign of growing social isolation. But even more important might be the impact on kids. 

In the United States, the picture is somewhat dark. Today, a growing share of children are born to cohabiting couples (about 20 percent now), and such children are approximately twice as likely to see their parents break up by the time they turn 12, compared to children born to married parents. What’s more, even among highly educated American couples with children, cohabitation is about twice as unstable as marriage: 49 percent of college-educated mothers will break up with their partner before their child turns 12 if they were cohabiting at the time of that child’s birth, compared to just 18 percent of mothers who were married at that point. In the United States, then, marriage comes with a substantial stability premium for children.

This matters because children are more likely to thrive on stable routines with stable caregivers. Family instability is, by contrast, risky. As sociologist Andrew Cherlin, one of the world’s preeminent family sociologists, observed, “Some children seem to have difficulty adjusting to a series of parents and parents’ partners moving in and out of their home.” Children who experience their parents’ breakup and then additional family transitions are, among other things, more likely to be unhappy and to be disruptive in school as well as to end up pregnant as a teenager and without a college degree.  It is precisely the endemic instability associated with cohabitation in the United States that has led family scholars to express concern. Richard Reeves, co-director of the Center on Children and Families at the Brookings Institution, has no moral qualms about cohabitation, but he is concerned by its relative instability in the United States. “The issue is the fragility of cohabiting vs. married relationships. Children born to cohabiting couples do worse because their parents are much more likely to break up,” Reeves said. “This instability is what damages children’s well-being.”  


Those who counter arguments like Cherlin and Reeves’ often point to Europe. There, especially in countries like Sweden and France—where cohabitation is common, long-standing, and legally sanctioned—cohabitation is seen to be about as stable as marriage for children. Cherlin, in his book The Marriage-Go-Round: The State of Marriage and the Family in America Today, argues that “long-term stable cohabiting relationships that seem like substitutes for marriage” are common in parts of Europe and are more stable than American marriages. In Scandinavia and France, Cherlin adds, “There are many long-term cohabiting parents who maintain families that are little different from lasting marriages.” Many professionals who have lived and worked in Europe also hold the view that cohabitation and marriage are functional equivalents there. Jamie Grant, a 43-year-old man whose work often brings him to Europe, had this to say about marriage and cohabitation: in Europe, “people have moved on from looking at marriage as a sacred pact. You don’t need this piece of paper to solidify your relationship. I don’t see any difference between my cohabiting and married friends. I don’t think people look at marriage as having that title that’s going to keep them together.” There is a problem with the view that cohabitation is as stable as marriage in much of Europe, especially when it comes to children. It doesn’t fit the facts. In our new report from the Social Trends Institute and the Institute for Family Studies, The Cohabitation-Go-Round: Cohabitation and Family Instability Across the Globe, we find that children across Europe are about 90 percent more likely to see their parents break up by age 12 if they were born to cohabiting parents compared to married parents. Indeed, across Europe, family instability tends to be higher for families formed by cohabitation, even for the kind of highly educated couples a professional like Grant is likely to encounter in his work. 

Take France. Overall, cohabiting couples are about 66 percent more likely to part ways before their children turn 12, compared to couples that had their children in marriage. But the marriage premium isn’t just reserved for less-educated or moderately educated French families. As the figure above indicates, it also applies to highly educated French families (where the mother has a college education or higher). In such families, by the time a child reaches age 12, only nine percent of children born into married families have seen their parents break up versus 18 percent of children born to cohabiting families. Higher levels of family instability among the cohabiting are found there even though France has had a civil unions law, which offers cohabiting couples an independent legal status to formalize their rights and responsibilities, since 1999. 

Even in Scandinavia, where cohabitation is quite common and long established, marriage is associated with more stability. In Norway, for instance, families formed by cohabitation are about 88 percent more likely to break up in the 12 years following childbirth than families formed by marriage. Such stability is evident among families at all education levels, as the figure above indicates.



Further south in Europe, such as in Italy, the marriage advantage is even stronger. Out of a sample of 10,853 Italian children in our data, the Harmonized Histories data set, none saw their parents divorce by the time they turned 12, whereas 13 percent of families formed by cohabitation split.

Family instability is important, even in Europe, because children are more likely to flounder socially and emotionally there when they are not raised in a stable, two-parent home. One study of parental breakups across 14 European countries—including France, Italy, and Norway—found that children whose parents broke up have a “probability of achieving a university degree that is on average seven percentage points lower than that of children from intact families.” Another study of such breakups in Norway found that boys and girls were more likely to engage in violent behavior, be sanctioned by teachers for misbehavior, and struggle with substance abuse if their parents broke up, compared to children from intact families. Research in the United Kingdom suggests that a parental divorce during childhood has a negative effect on adult mental health for men and women in their 20s and early 30s. The fact, then, that cohabitation is linked to greater family instability in much of Europe suggests that children born into cohabiting families are at greater risk of floundering than their peers born to married families.

To be sure, the story about marriage and family stability in Europe is not universal—cohabiting families, for instance, are equally stable in Bulgaria. But in 12 out of the 16 countries we studied in Europe, this marital stability premium applied to children in general as well as to children from highly educated families. The general demographic trends in Europe lend no support to the view that Europeans have figured out a way to beat marriage when it comes to family stability. 

Indeed, the unstable character of cohabiting families in Europe and North America led Patrick Heuveline, a French demographer based in UCLA, and his colleagues to conclude: “Perhaps the only universal Western trend is that childrearing is being shifted from married parents to single mothers more than to cohabiting parents, stepfamilies, or single fathers.” In other words, the rise of cohabitation, since it is likelier than marriage to end in a separation, has gone hand in hand with increased rates of single motherhood in the West.


The European pattern is worrisome because cohabiting families are on the rise, not just in Europe and the United States but also in many African and Latin American countries. In Mexico, for instance, the share of children born to cohabiting parents rose from 17 percent in 1990 to 38 percent in 2010. In South Africa, for example, the share of children born to cohabiting parents doubled from nine to 18 percent between 1996 and 2011.

Here again, our research finds cohabitation associated with more family instability. In a sample of more than 60 countries across the globe, we found that the share of children born to cohabiting parents was linked to lower levels of family stability—proxied by the share of children living with their biological parents at age 12. Even more telling, we found that, across the globe, increases over time in cohabiting families were associated with declines in the share of children living with their biological parents. For every percentage point increase in the share of children born to cohabiting families, the share of children living with both biological parents fell by 0.27 percentage points (most of the data on partnership context at birth were from the 1990s and most data on children’s living arrangements were from 2005 to 2015). The pattern was most salient for countries just seeing an initial spike in cohabitation—that is, those countries saw the biggest declines in the share of children living with both biological parents.

Babies who were born on New Year's day, lie on a bed inside the maternity ward of the Jose Reyes Memorial hospital in Manila January 1, 2014.
Babies who were born on New Year's day, lie on a bed inside the maternity ward of the Jose Reyes Memorial hospital in Manila January 1, 2014.
Romeo Ranoco / Reuters
This is worrisome because family stability seems to matter not only in the West but also in much of the developing world. Research indicates, for instance, that family instability is linked to higher child mortality across Africa, Asia, and Latin America. One study found that in a sample of children drawn from more than 20 countries in these three regions, “family instability is associated with an elevated child mortality risk of at least 20 percent.” Another study found that young teens were more likely to initiate early sex in Kenya when they experienced transitions in their caregivers at home. Studies like these suggest that an increase in families headed by cohabiting couples may pose a risk for children, not just in the West but across the globe, insofar as cohabitation is also linked to family instability outside of the West.

To be sure, our analyses cannot prove causation. Although we control for socioeconomic factors that might confound or distort the association between cohabitation and family instability—such as education, age, and, for the country-level analyses, degree of development—the rise of cohabitation is undoubtedly correlated with other factors, such as expressive individualism or a fear of commitment, that we were not able to measure. In practical terms, across much of the world, the kinds of parents today who are reluctant to fully commit are probably also more likely to simply live together and more likely to break up.

By showing that cohabiting families are more unstable, even among the highly educated in Europe and the United States, our research suggests family instability is not only about socioeconomic forces. As Pascal-Emmanuel Gobry observed in response to our findings on cohabitation, education, and family instability, “The point about educational status, in particular, is important: The vaguely pseudo-Marxist idea that our family and life outcomes are entirely driven by economics is not credible; values, norms, and institutions also matter.” And, at least today, the values and norms associated with the institution of marriage remain clearly and powerfully tied to family stability. That’s why, as marriage becomes less likely to anchor the adult life course across the globe, growing numbers of children may be thrown into increasingly turbulent family waters.

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  • W. BRADFORD WILCOX is Director of the National Marriage Project at the University of Virginia and a visiting scholar at the American Enterprise Institute. LAURIE DeROSE is research director of the World Family Map Project and a professor of sociology at Georgetown University.
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