The aim of this study was to identify the risk factors associated with low birth weight (LBW) in the city of Lubumbashi (DR Congo). This case-control study of singleton births took place from July to December 2014 in 3 referral maternity units in Lubumbashi. The mothers' social and demographic characteristics and medical and obstetric history, especially during this pregnancy, as well as the newborns' sex were compared between the case group (< 2500 g) and the control group. The usual statistics and logistic regression were used to analyze the results. The significance level was set at P < 0.05. We observed that a low educational level (OR adjusted = 2.5 [1.5-4.0]), employment (OR adjusted = 2.0 [1.3-3.1]), lack of prenatal care (OR adjusted = 2.5 [1.5-4.2]), maternal anemia (OR adjusted = 7.6 [2.3-24.8]), malaria during the pregnancy (OR adjusted = 1.5 [1.0-2.3]), urogenital infections during pregnancy (OR adjusted = 1.6 [1.1-2.5]), gestational hypertension (OR adjusted = 2.7 [1.5-4.9]), and maternal malnutrition (OR adjusted = 8.3 [2.4-28.5]) were all significantly associated with LBW. This study shows that some maternal demographic, medical, and obstetric factors influence the birth of LBW infants. Because some of these factors can be addressed and treated, the reduction of neonatal morbidity and mortality associated with LBW requires improving the health care system in our city, including its accessibility.