AbstractObjective:to analyze the trend of incompleteness of the maternal schooling and race/skin color variables held on the Brazilian Live Birth Information System (SINASC) between 2012 and 2020.Methods:this was an ecological time series study of the incompleteness of maternal schooling and race/skin color data for Brazil, its regions and Federative Units, by means of joinpoint regression and calculation of annual percentage change (APC) and average annual percentage change.Results:a total of 26,112,301 births were registered in Brazil in the period; incompleteness of maternal schooling data decreased for Brazil (APC = -8.1%) and the Southeast (APC = -19.5%) and Midwest (APC = -17.6%) regions; as for race/skin color, there was a downward trend for Brazil (APC = -8.2%) and all regions, except the Northeast region, while nine Federative Units and the Federal District showed a stationary trend.Conclusion:there was an improvement in filling out these variables on the SINASC, but with regional disparities, mainly for race/skin color.