Introduction: Globally, low birth weight (LBW) is prevalent in low-income countries. Although the economic assessment of interventions to reduce this burden is essential to guide health policies, research that illustrates the magnitude of LBW by country and region as a way to support the design of public policies is still relatively scarce. Objective: To analyze the temporal trend of fetal growth of newborns in Brazil, in the period from 2010 to 2020. Methods: A time series study, whose data source was the Live Births Information System (SINASC), of the Department of Information and Informatics of the Unified Health System (DATASUS), linked to the Ministry of Health, Brazil. The Prais-Winsten linear model was applied to analyse the annual proportions of LBW. The annual percentage changes (APC) and its respective 95% confidence intervals (95%CI) were calculated. To visualize the dynamics of evolution in each Federation Unit (FU), prevalence rate averages of LBW were calculated and displayed on thematic maps. Results: Between 2010 and 2020, there was a trend toward stabilization of the increasing proportions of low birth weight in the North, Northeast and Centre-West regions. In Brazil and the other regions these tendencies remained stable. Conclusion: To improve the living conditions of the population, public policies and actions aimed at reducing social inequalities and inequity is health are necessary, such as strengthening the Unified Health System (SUS), income transfer programs, quota policies for vulnerable groups, and gender to improve access to education for women and the labour sector.