Lead author John Cawley of Cornell University's College of Human Ecology and colleagues said the employed father devoted just 13 extra minutes daily to these activities with his children on days his partner worked an 8-hour day, while the non-working father contributed 41 extra minutes a day to his children on days his wife worked a full-time shift.
The findings were consistent across socioeconomic lines measured by the mothers' education, family income, race and ethnicity, Cawley said.
The findings might help explain some of the increase in child obesity because to make up for their lack of time, working mothers were significantly more likely to buy prepared foods -- takeout from restaurants or prepackaged, ready-to-eat meals from grocery stores -- which are generally less nutritious than home-cooked meals, Cawley said.
"It's inaccurate to pin rising childhood obesity rates on women, given that husbands pick up so little of the slack," Cawley said in a statement. "Working moms spend less time with their kids, but they also spent less time on themselves -- they spent 31 fewer minutes sleeping and less time watching TV, at leisure and socializing."
The study is to be published in the December issue of Economics and Human Biology.