Infant body mass index trajectories and asthma and lung function

Background: The impact of early rapid increase in body mass index (BMI) on asthma risk and subsequent lung function remains contentious, with limited prospective studies during a critical window for lung growth. Objective: Our aim was to investigate the associations between BMI trajectories in the first 2 years of life and adolescent asthma and lung function. Methods: Anthropometric data on 620 infants from the Melbourne Atopy Cohort Study were collected up to 18 times in the first 24 months of the study. BMI trajectories were developed by using group-based trajectory modeling. Associations between these trajectories and spirometry, fractional exhaled nitric oxide level, and current asthma status at 12 and/or 18 years of age were modeled by using multiple linear and logistic regression. Results: A total of 5 BMI trajectories were identified. Compared with those children with the "average"trajectory, the children belonging to the "early-low and catch-up"and "persistently high"BMI trajectories were at higher risk of asthma at the age of 18 years (odds ratios = 2.2 [95% CI = 1.0-4.8] and 2.4 [95% CI = 1.1-5.3], respectively). These trajectories were also associated with a lower ratio of FEV1 to forced vital capacity and a higher fractional exhaled nitric oxide levels at age 18 years. In addition, children belonging to the persistently low trajectory had lower FEV1 (13 = -183.9 mL [95% CI = -340.9 to -26.9]) and forced vital capacity (13 = -207.8 mL [95% CI = -393.6 to -22.0]) values at the age of 18 years. Conclusion: In this cohort, the early-low and 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.