According to the study from St Michael's Hospital, Toronto, children whose parents have high levels of stress have a Body Mass Index, or BMI, about 2 per cent higher than those whose parents have low levels of stress.
Children with higher parental stress also gained weight at a 7 per cent higher rate during the study period than other children.
Those figures may sound low, said lead author Dr Ketan Shankardass, but they are significant because they are happening in children, whose bodies and eating and exercise habits are still developing.
Shankardass studied data collected during the Children's Health Study, one of the largest and most comprehensive investigations into the long-term effects of air pollution on the respiratory health of children.
Also Read
Shankardass believes this is the first study to link parental stress to weight gain in such young children, adding it was not clear why the link between stress and obesity exists.
Parental stress could also create stress for the children, who cope by eating more or exercising less, or whose stress leads to biological changes that cause weight gain, he said.
"Childhood is a time when we develop inter-connected habits related to how we deal with stress, how we eat and how active we are," Shankardass said.
"It's a time when we might be doing irreversible damage or damage that is very hard to change later," said Shankardass.
The study was published in the journal Pediatric Obesity.