Combined effects of weight change trajectories and lifestyle factors on adiposity status at four years of age, a birth cohort study

Abstract

Background : Prior studies suggested that rapid weight change in infancy is associated with increased childhood and adulthood weight status. However, the weight change trajectory in early life over time and the extent to which childhood lifestyle behaviors may modify the risk of infant rapid weight change are not completely understood. Our aims were to characterize weight change trajectory early in life and explore its independent/combined effects with childhood lifestyle factors on adiposity outcomes at four years of age. Methods : In our ongoing birth cohort study, we used nine follow-up time points (birth, 3, 6, 9, 12, 18, 24 months, and 3, 4 years) to calculate the change between two adjacent weight for age z-scores ( WAZ-change ), and then to define WAZ-change trajectories using group-based trajectory modeling. The independent/combined effects of WAZ-change trajectories with each lifestyle factor ( eating behaviors , physical activity, media exposure time and total sleep duration) on childhood adiposity measures were determined using multivariate regression (where applicable). Results : A total of 84 (38.0%) children had a steady growth trajectory while the other 137 (62.0%) children had an early rapid growth trajectory most notable during the first six months. Compared to children with steady growth, children with early rapid growth had significantly higher adiposity status at four years of age - body mass index (β = 0.93, 95% CI: 0.59, 1.37), waist circumference (β = 1.90, 95% CI: 0.68, 3.12), and subcutaneous fat (β = 2.57, 95% CI: 1.13, 4.01). Moreover, WAZ-change trajectory not only had an independent effect, but also a combined effect with eating behaviors on most adiposity measures. Conclusions : We have identified two distinct weight change trajectories and described their independent and combined effects with eating behaviors on childhood adiposity measures. Larger samples and a longer period of observation through childhood are needed to replicate our findings.