Physical Activity And BMI Inequalities Throughout Childhood: A Brazilian Birth Cohort Study

PURPOSE: Utilizing the 2015 Pelotas (Brazil) Birth Cohort, the current study investigated differences in physical activity (PA) and BMI-for-age between sex, race/ethnicity, and socioeconomic status (SES) at ages 1, 2, 4, and 7. Further, this study explored differences in PA and BMI-for-age trajectories from 1 and 7 years based on these demographic variables. METHODS: Sex was collected at birth, race/ethnicity at 4 years and an assets index was used to determine SES. Height and weight were used to obtain BMI-for-age and PA was collected via wrist-worn accelerometers. Means and 95% confidence intervals described potential inequalities in PA and BMI-for-age between each demographic variable at all ages. Trajectory models revealed longitudinal patterns in PA and BMI-for-age differences from ages 1 to 7 years. RESULTS: Boys engaged in more PA and had higher BMI-for-age than girls at all ages. Starting at 2 years, black and brown children and poorer children engaged in more PA than white and high-SES children. Poorer children presented lower values of BMI-for-age at all ages. The trajectory models revealed four groups for PA in which boys, black and brown, and poorer children were more prevalent in the increasing and high PA groups. For BMI-for-age, five groups were found, revealing that boys and black and brown children were most prevalent in higher groups. CONCLUSIONS: The current study provides evidence of both PA and BMI-for-age inequalities across multiple demographic variables from ages 1 to 7 years. These results are an important part of understanding the role that sex, race/ethnicity, and SES may play in leading to childhood health disparities. Consequently, the present study may reveal when such inequalities begin to arise and aid in developing interventions to improve health behaviors for specific populations that may be at greater risk of a poorer health-related quality of life. Supported by: This study was funded by the Wellcome Trust, the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul, Children’s Pastorate, and the Department of Science and Technology (DECIT/Brazilian Ministry of Health).