Impact of time trends and increasing age on health behaviour of Swedish school children.

Background: Information on trends in healthy and unhealthy habits among children are important for the development of programmes intended to foster and consolidate a healthy lifestyle. This report studied the importance of time and age on the health behaviour of Swedish school children.

Methods: A comparison between health behaviours derived from repeated evaluations of Swedish school children aged 11-13 years was performed.

Results: Significant positive time trends were found in the form of increased physical activity and decreased sedentary behaviours, whereas negative time trends were observed in dietary habits and smoking. An analysis of the impact of increasing age demonstrated a negative influence including less physical activity and deteriorating dietary habits and increased smoking at the young age groups in this study.

Conclusion: Time trends and age are both important determinants of health behaviour in pre-teen children. Even the small age increase from 11 to 13 years had an important negative influence. The results of the present study underline that the window of opportunities to promote a healthy lifestyle in children is narrow. It is evident that a successful health intervention programme must be initiated at an early age, continued and repeated over time, and structured to counteract trends in age as well as time.