NEW YORK (MainStreet) – Are your kids chunky? It could be your fault, mom.

A new study published in the journal Child Development suggests that working mothers are partly to blame for their children’s weight problems.

The study, conducted by researchers at American University, Cornell and the University of Chicago, found a small positive correlation between mothers’ long workdays and their children’s body mass index (BMI).

“We find that maternal employment has a cumulative influence on children’s BMI that, over time, could lead to an increase in the likelihood that a child is overweight or obese,” write the study’s authors. Nonstandard employment – that is, work schedules that include nights and weekends – was particularly associated with obesity.

The child’s grade level also played a role in determining whether maternal employment would cause an uptick in obesity, with fifth and sixth graders faring particularly poorly when mom was working. “Among sixth graders, a mother’s entry into employment was associated with an increase in BMI of about two fifths (40%) of a standard deviation, and those children were about six times more likely to be overweight,” reads the report.

Nevertheless, the study is short on answers for why these associations exist. While the authors acknowledge existing theories that children with working mothers are more likely to watch TV or lead sedentary lifestyles, “there was no evidence that TV time or physical activity mediated this relation at either fifth or sixth grade,” they wrote. The authors did posit that children’s eating and sleeping habits may be affected by the work habits of mothers, but that data was not considered as part of this study.

Meanwhile, another study suggests that the seeds of childhood obesity are sown much earlier in the child’s life.

The study, published in the most recent issue of the journal Pediatrics, looked at the propensity for childhood obesity among children based on their nursing habits as infants. The study found that 9% of the 568 infants surveyed were considered obese by the time they reached three years of age. But whether or not they fell into this “obese” group was greatly influenced by when they were introduced to solid foods.

Those who were formula-fed as infants and then introduced to solid food before reaching four months were six times more likely to be obese at age three than other formula-fed infants weaned after four months.

However, those infants who were breast-fed did not show any correlation based on when they were introduced to solid food.

So, moms, iIf you’re going to bottle-feed your child, don’t be too eager to crack open the baby food jars. And try not to work long hours, especially when your kid is in sixth grade.

Of course, there may be an even simpler way of keeping your kids from becoming obese: Don’t let them eat fast food.

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