Infant Body Mass Index Trajectories, and Asthma & Lung Function.

Abstract Background The impact of early rapid body mass index (BMI) increase on asthma risk and subsequent lung function remains contentious, with limited prospective studies during a critical window for lung growth. Objective We investigated the associations between BMI trajectories in the first 2 years of life, and adolescent asthma and lung function. Methods Anthropometric data was collected up to 18 times in the first 24 months on 620 infants from the Melbourne Atopy Cohort Study. BMI trajectories were developed using group-based trajectory modelling. Associations between these trajectories and spirometry, fractional exhaled nitric oxide, and current asthma status at 12 and/or 18 years of age were modelled using multiple linear and logistic regression. Results Five BMI trajectories were identified. Compared to the “average trajectory”, children belonging to the “early low and catch up” and “persistently high” BMI trajectories were at higher risk of asthma at 18 years (OR=2·2; 95%CI 1·0, 4·8 and 2·4; 1·1, 5·3 respectively). These trajectories were also associated with lower FEV1 by FVC, and higher FeNO levels at 18 years. In addition, children belonging to the “persistently low” trajectory had lower FEV1 (β=-183·9 ml; 95%CI -340·9, -26·9) and FVC (β=-207·8 ml; -393·6, -22·0) at 18 years. Conclusion In this cohort, “early low & catch up” and “persistently high” trajectories were associated with asthma and obstructive lung function pattern in adolescence. Having a persistently low BMI at an early age was associated with a restrictive pattern. Thus, maintenance of normal growth patterns may lead to improved adolescent respiratory health.