Cohabitation before marriage risky

The U.S. divorce rate has held steady at 45 percent since 1981.

Jay Teachman, a sociology professor at Western Washington University, said age (older than 26) and education (a bachelor's degree) are far more important predictors of marital success than cohabitation, which he believes has no effect on divorce rate - except for one group. Serial cohabiters, those who have had more than one live-in romantic relationship, do have a significantly greater divorce risk, he says.

"These people are, just like the original cohabiters, the risk-takers, not as committed to unions," Teachman said. "They're more likely to cut bait when things go wrong."