The probability of a woman getting married by age 25 dropped to less than half as more Americans opt to cohabitate with their romantic partners rather than tie the knot, a U.S. government study shows.

The proportion of women living with men without marriage almost quadrupled to 11 percent as of 2010 from 3 percent in 1982, according to data released today by the Centers for Disease Control and Prevention. For men, the proportion rose to 12 percent in 2010 from 9 percent in 2002, said Casey Copen, a demographer at the National Center for Health Statistics.

The shift toward premarital living arrangements contributed to the delay in first marriage for both women and men. The recession that started in 2007 also may have played a role as young couples avoided the commitment because of unemployment and uncertain financial security. In 2006-2010, women and men married for the first time at older ages than in previous years.

"In today's economic climate, many young adults are reluctant to pull the trigger," said W. Bradford Wilcox, director of the National Marriage Project at the University of Virginia in Charlottesville, which monitors the health of marriage. "They may be unemployed or underemployed or not know what the future looks like. They're hedging their bets."