BMI, waist circumference at 8 and 12 years of age and FVC and FEV1 at 12 years of age; the PIAMA birth cohort study

Background: In adults, overweight is associated with reduced lung function, in children evidence on this association is conflicting. We examined the association of body mass index (BMI) and waist circumference (WC) at age 12, and of persistently (at ages 8 and 12 years) high BMI and large WC, with forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) at age 12. Methods: Height, weight, WC and FVC and FEV1 were measured during a medical examination in 1288 12-year-olds participating in the PIAMA birth cohort study. 1090 children also had BMI and WC measured at age 8. The associations between BMI and WC and FVC, FEV1, and FEV1/FVC ratio were studied using local and linear regression analyses, separately for girls and boys. The regression models were adjusted for age, height, and pubertal development and maternal educational level. Results: High BMI and large WC (sd-score >90th percentile) were associated with higher FVC; in girls these associations were statistically significant (4.6% (95% CI: 1.5, 7.9) and 3.6% (95% CI: 0.6, 6.8) respectively in adjusted models). Similar associations were observed for persistently high BMI or large WC: girls with a high BMI or large WC at both 8 and 12 years had statistically significantly higher FVC at age 12 years (BMI: 4.9% (95% CI 0.9, 9.1), WC: 5.0% (95% CI 0.7, 9.6)) than girls with normal BMI or WC at both ages. No statistically significant associations were observed between (persistently) high BMI or large WC and FEV1. The FEV1/FVC ratio was statistically significantly lower in children with a high BMI or large WC than in children with a normal BMI or WC. Girls and boys with a persistently high BMI or large WC status had statistically significantly lower FEV1/FVC ratios. Conclusion: At 12 years of age, a persistently high BMI or large WC is not yet associated with lower FVC and FEV1, suggesting that this association, that is commonly observed in adults, develops at a later age.