NEW YORK (Reuters Health) - The growing number of full-time working moms in the past few decades could be one of the factors contributing to the concurrent rise in childhood obesity, new research hints.
In a study of more than 8,500 UK adults followed since their birth in 1958, researchers found that the study participants' young children were 50 percent more likely to be overweight or obese than they themselves had been back in the 1960s.
When the researchers looked at factors that could be associated with the trend, they found that mothers' full-time employment, which was more common in the younger generation, appeared to be one.
The findings, published in the American Journal of Epidemiology, do not prove that moms' full-time work, per se, contributes to the risk of childhood obesity.
One possibility, according to the researchers, is that children of full-time working moms have fewer family meals or less-healthy diets in general.
So the trend in mothers' employment over the past few decades may be one of the variables contributing to a general erosion in children's diets; the explosion in sugary junk foods on the market, food advertising aimed at kids, and the increasing availability of high- fat, high-sugar fare in schools are among the other factors that have been blamed.
The current study lacked information on the children's diets and exercise habits, so it is not known whether kids of working moms did in fact have poorer-quality diets or were less active.
For the study, Dr. Leah Li and colleagues at the University College London analyzed data from a project that has followed a large group of Britons since their birth in 1958. They focused on 8,552 participants who, in 1991, had a total of 1,889 children between the ages of 4 and 9.
Overall, the children were more likely to be overweight or obese than their parents had been back in 1965: 12 percent of boys were overweight or obese, versus 8 percent of their fathers in childhood; and 18 percent of girls were heavy, versus of 11 percent in their mothers' generation.
Li's team found that both parents' current weight and mothers' employment status were associated with the risk of their children being overweight.
Children of mothers who worked full-time were 48 percent more likely to be overweight or obese than children of non-working mothers. That was with factors such as socioeconomics, parents' weight and breastfeeding (which some studies have linked to a lower risk of childhood obesity) taken into account.
When parents were obese, the odds of the child being overweight were three to six times greater than when parents were normal-weight.
Rates of both parental obesity and full-time work among mothers increased between the two generations. In 1991, 60 percent of mothers worked, including 15 percent who were full-time; that compared with 45 percent and 10 percent, respectively, in 1965.
Similarly, about 12 percent of parents were obese in 1991, versus 5 to 7 percent of the first generation's parents in 1965.
So it's possible, according to Li and her colleagues, that both factors (parents' weight, in particular) contributed to the intergeneration increase in childhood weight.
However, even if mothers' employment is a factor in the rise of childhood obesity, it would only account for a small portion of that increase, the current findings suggest.
Based on their data, the researchers estimate that in 1991, less than 8 percent of cases of childhood overweight or obesity could be attributable to mothers' employment.
In general, experts believe that a complex mix of societal factors -- from shifts in eating habits, to greater reliance on cars and increasing hours logged in front of the TV or computer -- has been behind the rise in childhood weight problems in recent decades.
American Journal of Epidemiology, online May 20, 2010.