The objective of this article is to estimate the prevalence and factors related to the risk of Low Birth Weight (LBW), and its impact on socioeconomically disadvantaged populations. A cross-sectional, analytical study was used, based on data available in the Information Technology Department of the Unified Health System (DATASUS), more specifically, in the Live Birth Information System (SINASC). For data analysis, the EPI-INFO 7.0 program was used, where bivariate analysis was used with the Chi-square test considering the Mantel-Haenszel method to identify which factors are associated with LBW. 49,481 live births were examined in the State of Mato Grosso, 8.78% of which were affected by LBW. In the bivariate analysis, LBW was mostly recorded in children of pregnant women who were in the risk age group, marital status in which they lived alone/separated, indigenous race or skin color, black or mixed race, and lived in a region with low HDI . Furthermore, there are other factors related to pregnancy that had a strong influence on LBW, including: number of prenatal consultations and type of pregnancy. Regarding the characteristics of newborns, LBW presented a majority in female babies and those born prematurely and/or with malformations or congenital anomalies. The results found in the present study justify the need to improve actions capable of serving the maternal and child population so that economic and demographic factors have less impact on the occurrence of LBW.