This is just one of eight aspects of early life found to be linked to obesity in UK children, and these results support the theory that the early life environment can determine later risk of obesity.
The study involved 8,234 children aged 7 years and a further sample of 909 children who were taking part in a large UK study of parents and children. Height and weight were measured and body mass index (BMI) was calculated.
In the entire group, four factors were independently associated with a risk of obesity at age 7:
A further four factors were significant for the children in the additional sample:
The precise mechanisms by which these variables might increase the risk of obesity are complex, say the authors. For instance, parental obesity may increase the risk of obesity through genetics, or by shared family characteristics in the environment such as food preferences.
Duration of night time sleep may affect growth hormone secretion or reduce the child's exposure to food intake in the evening. Alternatively, children who are more physically active may sleep longer at night. Finally, television viewing may confer risk through a reduction in energy expenditure or an increase in dietary intake.
"Our study provides evidence of the role of the early life environment in the later risk of obesity," say the authors.
"Most interventions to prevent obesity have tried to change lifestyles of children and adolescents and have been unsuccessful. Future interventions might focus on environmental changes targeted at relatively short periods in early life, attempting to modify factors during pregnancy, in infancy, or in early childhood, which are independently related to later risk of obesity."