FRIDAY, February 4 (Health.com) — Over the past 35 years, the percentage of U.S. mothers who hold down a job while raising kids has soared, from less than 50% to more than 70%. The childhood obesity rate—which is now close to 17%—has more than tripled during the same time frame.
These overlapping trends may not be a coincidence. The longer a mother is employed, the more likely her children are to be overweight or obese, a new study of grade-schoolers published in the journal Child Development suggests.
For each additional five-month period his or her mother is employed, a child of average height can be expected to gain 1 extra pound over and above normal growth, the study estimates. In addition, sixth graders with working mothers were found to be six times more likely than those with stay-at-home moms to be overweight.
Mothers who have jobs don’t directly cause weight problems in their children, but busy families may accelerate weight gain by relying too much on fast food and frozen dinners rather than preparing fresh, healthy meals, the researchers say.
“It is not the mother’s employment, but the environment,” says the lead author of the study, Taryn Morrissey, PhD, an assistant professor of public administration and policy at American University in Washington, D.C. “There needs to be improved access to healthy foods.”
Focusing on kids in grades 3, 5, and 6, Morrissey and her colleagues analyzed data from a government-funded study that began in 1991 and followed more than 1,000 children nationwide from infancy through age 15. As part of that study, researchers interviewed families about their everyday lives and measured the children’s body mass index (BMI), a simple ratio of height to weight that estimates total body fat.
Roughly three-quarters of the mothers in the study were employed, and they were working an average of 27 hours per week when their children were in third grade. More than 80% of mothers were married or living with a partner, and 90% percent of those husbands or partners worked full time.
The study didn’t collect data on family eating habits, so Morrissey and her colleagues weren’t able to confirm their hunch that diet is largely responsible for their findings. But they were able to effectively rule out several alternative explanations.
None of the factors the researchers looked at—including average time spent in front of the TV, daily physical activity, and parental supervision—helped explain the link between a mother’s employment and her child’s BMI. Nor did it seem to matter whether the mother worked a standard 9-to-5 schedule (as opposed to night shifts, for instance).
Next page: Eating habits may be to blame