Longitudinal approaches for analysing childhood body mass index trajectories

This dissertation investigates the development of body mass index (BMI) across childhood and its genetic determinants. In the first study, a framework was developed to model BMI trajectories in children in different populations. Additionally, new variables – the average change and cumulative BMI – were derived and analysed over four time periods: infancy, early childhood, late childhood, and adolescence. These variables were tested in a genome-wide association study (GWAS), which identified 28 genetic markers at 13 loci. The second study identified three distinct developmental patterns in childhood BMI trajectories, two of which are novel findings. These patterns reflect differences in the pace at which BMI changes in children over time.

The Northern Finland Birth Cohorts 1966 and 1986 were used as the primary study population. The first study was further complemented with international cohorts from varied settings. The inclusion of diverse cohorts demonstrated the framework’s applicability across populations, accounting for genetic and environmental differences in child growth.

The research enhances current understanding of the individual development of childhood BMI and the genetic factors involved. The findings may support more precisely targeted approaches to obesity prevention and treatment at an early stage.