Over the years, many studies have searched for what ingredients make a happy and lasting marriage. For some time, however, living together before marriage was an indicator that the union was more likely to end in divorce than one where the couple shared a residence only after the marriage ceremony. A new study released by the Centers for Disease Control and Prevention, however, shows that is no longer true.

Today, couples who share a residence and are engaged before marriage are just as likely to have a marriage that reaches at least 15 years as those who do not cohabitate before the wedding. But the results are different for those who are not engaged. Men and women who live with their future spouse without being engaged first are not as likely to stay married for 15 years.

This contrast perhaps says less about engagement as a guarantee of future marital success than it does about couples who decide to get engaged first. In other words, engagement does not cause long-lasting marriages, but is merely correlated with them. It may indicate that the underlying relationship between engaged couples is strong enough to reach certain milestones in greater numbers.

Researchers suggested that the increase in cohabitation before marriage–which has risen to 60 percent from just 10 percent in the late 1960s–may be due in part to shifting patterns in career development. More people are seeking college degrees and looking to create a solid career foundation after school. By implication, couples are now putting off marriage and children until a later age than earlier generations. Yet modern couples still live together in a kind of “trial marriage” before actually tying the knot.

The study also revealed additional figures about marriage. Despite the increased marital success of some couples who live together beforehand, approximately one in two couples will get divorced before they reach their 20th anniversary. Divorce can be complex, with couples having to contend with division of property and, if they are parents, child support and custody.

Source: Associated Press, “Move-in Before Marriage No Longer Predicts Divorce,” Mike Stobbe, Mar. 22, 2012.