Objectives: To explore the relationship between sociodemographic variables present in the mother and in the family with low birth weight infants attended at a university clinic in Chia, Colombia. Methods: Cross-sectional study. 301 newborns from the Clinica Universidad de La Sabana were included between July 1 and December 31, 2015. Socio-demographic variables and maternal and newborn factors were analyzed. A bivariate analysis was performed to determine the relationship between the variables and low-birth weight, the chi2 or Fisher test was applied. A logistic regression model was performed to explore the association between exposure variables and low birth weight. Results: The frequency of low birth weight was 18.27 %. We found an association between low birth weight and low maternal education (OR 2.65, 95 % CI: 1.17 - 5.97). As a protective factor for birth weight was found to attend four or more prenatal controls (OR 0.34, 95 % CI: 0.14 - .084). Conclusions: The frequency of low birth weight is above the national and regional average. The low educational level was found as a risk factor and as a protective factor the number of prenatal controls. It is important to continue with adequate social control in low-income mothers and families as a primary preventive factor of low birth weight.