A generation ago, unmarried couples who lived together were often derided for "shacking up" or "playing house." Studies in the 1980s supported those negative stereotypes, suggesting that cohabitation could doom a long-term relationship, substantially raising the risk of divorce.
While researchers say the overall divorce rate is higher among those who lived together before marriage, now they don't blame cohabitating.
"There's been a sea change in societal, cultural and individual acceptance of cohabitation," says Pamela Smock, a sociologist at the Population Studies Center at the University of Michigan-Ann Arbor. "A lot of the earlier studies were relying on data that may have been gathered in the late '80s and mid-'90s. We're talking about a moving target. The evidence is a lot more mixed."
Researchers say changing times have produced more extensive information about cohabiters and more sophisticated research methods.
Census data out today show 9.6 percent of all opposite-sex couples living together in 2007 were unmarried. "Cohabitation has become a common experience in people's lives," Smock says.
"The nature of cohabitation has changed," says Jay Teachman, a sociology professor at Western Washington University in Bellingham. "Cohabitators 20 years ago were the rule breakers, the rebels, the risk takers — the folks who were perhaps not as interested in marriage, and using cohabitation as an alternative to marriage."
"Twenty or 25 years ago, if you were cohabiting and then married them, the marriage was more likely to dissolve and end in divorce," he says. "Today, that's not the case. You can cohabit with your spouse and not experience increased risk of divorce. We're making these finer distinctions that we didn't make before."
Teachman's analysis of federal data on 6,577 women whose first marriages occurred between 1970 and 1995 found that a woman who has lived only with her future spouse has no greater risk of divorce. But for women who lived with someone else in addition to the eventual husband, there is a greater risk of divorce, found the study, published in 2003.
Those aren't the only studies reflecting changes — researchers across the country, including at the University of Wisconsin, the University of Minnesota, Pennsylvania State University, Cornell University and others, are studying cohabiting couples. Among other recent findings:
The odds of divorce among women who married their only cohabiting partner were 28% lower than among women who never cohabited before marriage, according to sociologist Daniel Lichter of Cornell University in Ithaca, N.Y.
Divorce rates for those who cohabit more than once are more than twice as high as for women who cohabited only with their eventual husbands, says Lichter's study, to be published in the Journal of Marriage and Family in December.
Cohabiting between a first and second marriage doesn't raise the risk of divorce — unless the woman brings a child into the marriage from a previous relationship. A man with a child from a previous relationship does not raise the likelihood of a second divorce, finds a study in the May Journal of Marriage and Family, in which Teachman analyzed findings on 655 women from the 2002 National Survey of Family Growth.
Other recent studies have shown that certain subgroups don't appear to experience negative effects from cohabiting, such as engaged couples who move in together or those who have already decided to marry in the future.
Some new research goes further, suggesting that living together may reduce risk of divorce.
"We showed women who only cohabited with their husband had lower rates of divorce than women who didn't cohabit and went straight to marriage," Lichter says. "There seems to be less risk than if you cohabit many times or if you don't cohabit at all." An academic paper on that lower divorce risk for cohabiters is forthcoming, he says.
His research on serial cohabitation analyzed data from the National Longitudinal Survey of Youth and found that women living with even one more man in a romantic relationship other than the eventual spouse increased divorce risk.
Sociologist Kelly Musick, also from Cornell, says the focus on cohabitation research is shifting.
"The emphasis in the cohabitation literature for a very long time was on trying to understand why couples who cohabit before marriage split up at higher rates than those who don't," she says. "More recent studies have tried to understand more about what it means and look at it more as a family form in its own right."