Trajectories of Device-Measured Physical Activity During Early Childhood and Its Determinants: Findings From the 2015 Pelotas (Brazil) Birth Cohort Study.

BACKGROUND

The objective was to describe trajectories of physical activity (PA) measured by accelerometry during early childhood and to test associations with sociodemographic, gestational, maternal, and perinatal determinants.

METHODS

Data from 1798 children from the 2015 Pelotas (Brazil) Birth Cohort were analyzed. PA was measured with wrist accelerometers at 1, 2, and 4 years. PA trajectories were estimated using group-based trajectory modeling, and associations with determinants were tested using Poisson regression with robust variance.

RESULTS

Two trajectories were identified: Moderate and high PA, both showing a linear increase in PA in the first years but differing in volume. Girls (prevalence ratio [PR]: 0.91; 95% confidence interval [CI], 0.88-0.94), highly educated mothers (PR: 0.93; 95% CI, 0.88-0.97), and high birth weight children (PR: 0.91; 95% CI, 0.85-0.97) showed less probability of high PA trajectory. Birth order ≥3 (PR: 1.06; 95% CI, 1.01-1.11) was associated with higher likelihood of high PA trajectory.

CONCLUSIONS

Children showed an increase in PA during the first years, with 2 trajectories that differ in PA levels. Female sex, high maternal schooling, and high birth weight reduced the probability of having a high PA trajectory, while higher birth order increased this probability. These characteristics should be considered when planning PA interventions for children in early childhood.