Abstract
AIM: Development of body mass index (BMI) trajectories is essential for understanding childhood overweight, a public health concern. This study aimed to identify BMI trajectories from birth to adolescence and examine associated factors in the Pollution and Asthma Risk: an Infant Study (PARIS) birth cohort. METHODS: Data on height, weight, birth parameters, lifestyle, parental weight status and stress were collected via questionnaires and health check-ups. BMI z-score (BMIz) trajectories were developed using group-based trajectory modelling on anthropometric data collected at least six times. Associated factors were investigated in multivariable multinomial logistic regression models, adjusted for confounders. RESULTS: Five BMIz trajectories were identified in 540 adolescents. The early high stable BMI trajectory grouped participants who reached overweight status in early childhood. Four trajectories remained within the normal weight status: low stable BMI, continuous decrease BMI, continuous increase BMI, and early increase and slight decrease BMI trajectories. Compared with low stable BMI, high BMI trajectories were associated with higher parental weight status, early rebound age, excessive TV watching, lower food avoidance score, stressful events in early life and parent-child relationship stress. CONCLUSION: High BMI trajectories shared several modifiable factors, emphasising the need for multifactorial interventions to tackle the childhood overweight epidemic.