Twenty-nine percent of U.S. mothers, or about 10.4 million women, stayed at home in 2012. That is up from a low of 23 percent in 1999, and marks a turnaround from three decades of decline.
The category of stay-at-home mothers with children under 18 includes women who are at home to care for their families and mothers who cannot find work, are disabled or in school, the Pew Research Center analysis of Census Bureau data said.
Six percent of stay-at-home mothers, or about 634,000 people, said they were home with their children in 2012 because they could not find a job. That share is six times larger than it was in 2000.
The U.S. economy's slow recovery from the recession of 2007-2009 lead many Americans to give up looking for work, a trend that has changed over the past six months as people regain confidence in the job market.
The Pew analysis underscores women's declining share of the U.S. work force. Labor Department numbers show that 57.2 percent of women have a job or are looking for one, down just over 2 percentage points in a decade.
"With incomes stagnant in recent years for all but the college-educated, less educated workers in particular may weigh the cost of child care against wages and decide it makes more economic sense to stay home," the Pew analysis said.
The rising share of stay-at-home mothers also could be caused by the increasing number of immigrants, who made up 13 percent of Americans in the 2010 U.S. census.
A third of stay-at-home mothers are immigrants while immigrants make up only one in five working mothers.