When it comes to cooking, grocery shopping and playing with children, moms with full-time jobs spend roughly three-and-half fewer hours per day on these and other chores related to their children's diet and exercise compared to stay-at-home and unemployed mothers.

Their male partners do little to make up the deficit: Employed fathers devote just 13 minutes daily to such activities and non-working fathers contribute 41 minutes, finds the study published online June 23 in the journal Economics and Human Biology (10:4). The findings are consistent across socio-economic class measured by the mothers' education, family income, and race and ethnicity.

To make up for this gap, working mothers are significantly more likely to spend time purchasing prepared foods -- takeout from restaurants or prepackaged, ready-to-eat meals from grocery stores -- which are generally less nutritious than home-cooked meals.

Past research has shown links between women entering the workforce and childhood obesity -- the rates of both have grown sharply in the United States since the early 1970s -- but the paper is the first to show the difference in time spent by working and non-working mothers on activities related to their children's diet and physical activity. These differences in time allocation represent plausible mechanisms by which maternal employment could affect childhood obesity.

However, cautioned lead author John Cawley (right), professor of policy analysis and management and of economics in the College of Human Ecology, "it's inaccurate to pin rising childhood obesity rates on women, given that husbands pick up so little of the slack."

And, Cawley said, the study does not prove that employment alone drives the way mothers spends their time. "For example, mothers who choose to work might be those who enjoy cooking less and who would cook less whether working or not," he said.

He added that working mothers produce additional benefits for children such as more money to provide for family needs.

"It's important to remember that we can take steps to enhance childhood nutrition and physical activity without advocating that women exit the workforce," Cawley said. For instance, the authors argue, parents should be better educated about the nutritional content of restaurant and prepackaged foods. "In order to make more informed decisions, consumers need to have nutrition and calorie information available where they buy their food," said Cawley, who noted that federal health care reform rules will soon require chain and fast-food restaurants nationwide to post calorie counts of the foods they sell.

And Cawley noted that schools shoulder a greater burden for supporting healthy lifestyles.

"Our findings underscore the importance of schools offering high-quality foods and physical education classes," he said. "In general, the Institute of Medicine and the Centers for Disease Control and Prevention are urging comprehensive changes in school environments to promote healthy eating and active living."

For the paper, Cawley and co-author Feng Liu, Ph.D. '07, assistant professor of health economics at Shanghai University of Finance and Economics (SHUFE), analyzed a sample of 24,902 women with at least one child under age 18 living at home. They also studied data from the American Time Use Survey from 2003-09, an annual survey that asks U.S. adults to account for every minute spent during a typical 24-hour period.

The research was funded by the College of Human Ecology's Institute for Health Economics, Health Behaviors and Disparities and by SHUFE.

Ted Boscia is assistant director of communications for the College of Human Ecology.

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