Objective: The aim was to assess the risk factors and prognosis of low birth weight at nianankoro Fomba Hospital in Ségou, Mali. Materials and Methods: This is a prospective control case study from January 1, 2011 to December 31, 2011. Results: We recorded 160 infants of low birth weight out of a total of 2353 births or 6.8%. Adolescent girls were the most affected with 35% of cases compared to 16.9% for witnesses. Brides were the most affected in 80.6% of cases compared to 92.2% among witnesses. The main reasons for consultation were uterine contractions in 43.8%; metrorragia on pregnancy in 12.5% of cases and premature rupture of membranes in 10% of cases. Low birth weights were observed in discharged parturients in 35% of cases were compared to 8.1% of controls 36.25% of pregnant women who performed only one antenatal consultation (CP NV) had given birth to a low birth weight compared to 12.3% in controls and 60.63% of cases had not performed any NPCs compared to 4.3% in controls. Instrumental extraction was performed in 43% of cases compared to 15.6% in controls, and caesarean section in 26% of cases versus 5.9% in controls. It appears that both sexes were affected by low birth weight with a predominance of the male sex (56.9%) compared to women (43.1%). The main causes of neonatal death were among others: Respiratory distress with 62.22% and neonatal infections in 26.66%. Conclusion: Infants of low birth weight are a public health problem because of their high prevalence and the resulting adverse consequences.