– American mothers are reversing a historical trend and increasingly staying out of the workforce in a change driven by demographic, societal and economic forces — including the worst recession in seven decades.

The share of mothers with children under age 18 who don't work "outside the home" rose to 29 percent in 2012, up from a modern-era low of 23 percent in 1999, according to a report released Tuesday by the Pew Research Center.

The trend follows a decline in stay-at-home moms recorded in most years from 1970 to 1999, as more women entered the workplace, spurred both by a sense of empowerment and financial demands.

The recession that produced dramatic job losses kept some mothers out of the workforce as they struggled to find work. Others found it more advantageous to stay home after weighing the cost of child care against wages. Weekly child-care costs rose to $148 in 2011 from $87 in 1985, Pew said.

"The majority of mothers would like to be in the workplace," said D'Vera Cohn, lead author of the report, which used a variety of census and survey data. "There may be a ceiling to how much stay-at-home motherhood can increase."

The weak economic recovery also has also taken a toll on working men.

The employment ratio for men 20 and older, which represents employment as a percentage of the working-age population, was 67.8 percent in March, down from 72.5 percent in December 2007, when the recession began. For women, the rate was 55.2 percent in March, down from 58 percent.

The sort of mothers portrayed along Wisteria Lane in the "Desperate Housewives" television series are a minority. Among stay-at-home moms with working husbands in 2012, just 22 percent had family incomes of $100,000 or more.

Those living in poverty are more common, with a third of stay-at-home mothers at that level of income, compared with 12 percent of working mothers. A growing share — 6 percent in 2012, compared with 1 percent in 2000 — say they're at home because they can't find a job.

Rise stopped in 2005

The share of mothers at home with children rose from 2000 to 2004, reflecting a growing economy and an increasing Hispanic population that includes a stronger tradition of stay-at-home mothers. The rise stopped in 2005 before economic uncertainty foreshadowing the recession's official 2007 beginning.

Asian and Hispanic children were the most likely to be raised by stay-at-home mothers — 37 percent and 36 percent, respectively — in 2012. That compares with 26 percent of white children and 23 percent of black children.

In 2012, 42 percent of stay-at-home mothers were younger than 35, compared with 35 percent of working mothers. Half of stay-at-home moms care for at least one child 5 or younger.

Pew's stay-at-home mother category includes those who say they're at home to care for families, as well as those who are unable to find work.

Stay-at-home moms are more educated than their predecessors decades ago, with a quarter now having college degrees, compared with 7 percent in 1970, the report said.

The data show 28 percent of children in 2012 were being raised by a stay-at-home mother, up from 24 percent in 2000. In 1970, 48 percent of children had a mother who stayed home.

Just one in five children today are living in a household with a married stay-at-home mother and her working husband. In 1970, 41 percent of children lived in that type of household. About 5 percent of mothers at home are cohabitating with a non- marital partner and 7 percent are married with husbands who don't work.

Public opinion has grown more supportive of working mothers over the past four decades as the practice became more common.

Shifting attitudes

When the National Opinion Research Center at the University of Chicago first asked in 1977 whether a working mother "can establish just as warm and secure a relationship with her children" as a mom who stays home, only half of Americans agreed. That share generally rose until 1994, when it reached 70 percent, and has continued at that level or higher.

Stay-at-home mothers spend an average of 18 hours per week caring for children, seven more than working mothers, according to American Time Use Survey data that Pew cites in its report.

They also spend nine hours more a week than working mothers on housework and have nine more hours a week of leisure time and five more hours per week to sleep.

"Financially it didn't make sense because my paycheck was going to basically be going straight to day care," said Shannon Puri, 34, a suburban Chicago mother of two who in 2010 left her job as a middle school special education teacher.

After trying baby sitters and day care for a year, Puri and her husband, a dentist, decided to have her stay home full-time.

"When I was at work I was thinking about things with my son, and when I was with him, I was catching up on things from the workday," she said. "I couldn't balance things well."