Effects of birth weight on body composition and overweight/obesity at early school age.

OBJECTIVES

The prevalence of childhood obesity has increased substantially. We aimed to characterize the effect of birth weight on body composition and overweight/obesity at early school age.

STUDY DESIGN

A total of 1669 children with available birth records from a double-blind cluster-randomized controlled trial exploring micronutrient supplementation during pregnancy were included. Data regarding school-aged body composition, social-demographic factors and health behaviours were prospectively collected.

RESULT

s: The study population consisted of 1004 boys and 665 girls aged between 7 and 10 years. The prevalence of overweight/obesity (>85th age-sex-specific percentiles) was 7.4% for boys and 5.0% for girls. Generalized estimating equation models were used to account for the cluster nature of the data. A significant upward trend across quintiles of birth weight was observed for fat mass index (boys: P for trend 0.002; girls: P for trend <0.001), fat-free mass index (boys: P for trend <0.001; girls: P for trend <0.001), and percentage of body fat (boys: P for trend 0.003; girls: P for trend <0.001). A birth weight in the higher three quintiles could increase the risk ratios [RRs (95% CI) third quintile: 2.88, (1.13, 7.32); fourth quintile: 2.40, (0.87, 6.66); top quintile: 2.31, (0.92, 5.80)] of overweight/obesity at early school age compared with the RRs of the reference group (the second quintile of birth weight) among boys.

CONCLUSIONS

Higher birth weight could increase the risk of being overweight/obese among 7- to 10-year-old boys in rural western China. Sex differences in this association need to be considered when planning interventions.

RESEARCH REGISTRATION

This trial was registered at www.isrctn.com with the identifier ISRCTN08850194.