Recent changes in growth trajectories: a population-based cohort study of over 5 million Brazilian children born between 2001 and 2014.

ABSTRACT

Background: There is limited evidence on recent trends in childhood growth trajectories in Low-/middle-income countries. We investigated how age-trajectories for height and Body Mass Index (BMI) have changed among Brazilian children born in two different time periods after 2000. Methods: We used a population-based cohort (part of the "Cohort of 100-Million Brazilians") created by the linkage of three Brazilian administrative databases the Cadastro Único of the Federal Government, the National System of Live Births and the National Nutritional and Food Surveillance System. We included longitudinal data on 5,750,214 children who were 3 to <10 years of age and born between 2001 and 2014 (20,209,133 observations). We applied fractional polynomial models with random-effects to estimate mean height and BMI trajectories for children. Findings: Compared to children born in 2001-2007, the cohort born in 2008-2014 were on average taller, by a z-score of 0.15 in boys and 0.12 in girls. Their height trajectories shifted upwards, by approximately 1 cm in both sexes. Levels of BMI increased little, by a z-score of 0.06 (boys) and 0.04 (girls). Mean BMI trajectories also changed little. However, the prevalence of overweight/obesity increased between cohorts, e.g., from 26.8% to 30% in boys and 23.9%-26.6% in girls aged between 5 and <10 years. Interpretation: An increase of 1 cm in mean height of Brazilian children during a short period indicates the improvement in maternal and child health, especially those from low-income families due to the new health and welfare policies in Brazil. Although mean BMI changed little, the prevalence of child overweight/obesity slightly increased and remained high. Funding: This work was supported by National Council for Scientific and Technological Development - CNPq; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES; National Institute for Health Research (NIHR) Great Ormond Street Hospital Biomedical Research Centre; Society for the Study of Human Biology; Fundação de Amparo à Pesquisa do Estado de Minas Gerais - FAPEMIG; Departamento de Ciência e Tecnologia da Secretaria de Ciência, Tecnologia, Inovação e Complexo da Saúde do Ministério da Saúde - Decit/SECTICS/MS. The study also used resources from the Centre for Data and Knowledge Integration for Health (CIDACS), which receives funding from the Bill & Melinda Gates Foundation, the Wellcome Trust, the Health Surveillance Secretariat of the Ministry of Health and the Secretariat of Science and Technology of the State of Bahia (SECTI-BA).