Do conflicting demands from work and family increase attrition rates among working mothers? Yes, reports Youngjoo Cha, assistant professor in the Department of Sociology at Indiana University at Bloomington. Plus, there's an added twist. "Mothers were 52 percent more likely than other women to leave their jobs if they were working a 50-hour week or more, but only in occupations dominated by men," says Cha.

Her study, "Overwork and the Persistence of Gender Segregation in Occupations," published in the April issue of Gender & Society, analyzed data collected from the Survey of Income and Program Participation conducted by the U.S. Census Bureau. The survey includes 382 occupations, 173 of which are considered male-dominated in that men made up 70 percent or more of the workforce. "Many of these are lucrative fields, such as law, medicine, finance and engineering," says Cha.

She intended her study to investigate whether working long hours perpetuates gender segregation in occupations. While "overwork" (50 hours or more per week) is an expected norm in many male-dominated occupations, mothers, whose time is often subject to more family demands than father's, are less able to meet this expectation.

Overworked mothers are not only more likely to leave a job in more masculine professions but her results also show that they are more likely to exit the labor force entirely. This pattern is specific to mothers and the same effect is not found for childless women. The study also assets that in male-dominated occupations, overwork is more likely than in female-dominated fields or balanced (equal men and women) fields.

In her earlier research, Cha has discovered that when husbands overwork, the effect is more limited contributions to responsibilities at home and restrictions placed on the wife's time for work outside the home. When a wife overworks, though, the husband's work is rarely affected according to her research. More than one-third of men and nearly one-fifth of women in professions work more than 50 hours a week.

Findings from a 2011 survey posted on the Bureau of Labor Statistics website indicate that among full-time workers (those usually working 35 hours or more per week in undifferentiated professions), men worked longer than women on the days that they worked-8.3 hours compared with 7.8 hours.

Statistics also show that 21 percent of employed persons did some or all of their work at home, and 85 percent did some or all of their work at their workplace. Men and women were about equally likely to do some or all of their work at home.