Aim: This study was done to assess the maternal and sociodemographic factors associated with LBW babies, an important indicator of maternal and newborn health in Bihar, India. Material and methods: Material and methods: This case control study was done the Department of Paediatrics, Anugrah Narayan Magadh Medical College and Hospital, Gaya, Bihar, India for 8 months. total 100 cases (mothers having LBW singleton babies) and 100 controls (mothers having normal birth weight singleton babies) were include in this study. Results: A total of 200 case and 100 matched controls were studied. Maximum 65 (65%) matched pairs of mothers were in the age group of 20-25 years, 61 (61%) matched pairs of mothers were primipara and 26 (26%) matched pairs of mothers delivered at 39 completed weeks of gestation while 24 (24%) mothers delivered at 40 completed weeks of gestation. The risk from various maternal factors as determined by Odds Ratio (OR) and Attributable Risk Proportion (ARP) in order of decreasing order was unfavourable outcome of previous pregnancy (OR=2.51), place of residence (rural) (OR=2.11), height <145 cms (OR=1.88), weight <40 kgs (OR=1.91), birth interval of <24 months (OR=1.77), WHPI d”100 (OR=1.81), Hb level <11 gram% (OR=1.62), BMI <18.5 kg/m2 (OR=1.53) and presence of any morbid condition during current pregnancy (OR=1.43). After MLR only 3 maternal factors i.e. place of residence (rural) (AOR=2.22), unfavourable outcome of previous pregnancy (AOR=1.88) and presence of any morbid condition during current pregnancy (AOR=1.51) were observed to be significant risk factors when adjusted for all other risk factors. Mother’s education, occupation, socio-economic status, physical activity during pregnancy (light, moderate & hard), sleep & rest duration, age at marriage, tobacco consumption, time of registration of pregnancy, number of ANC visits, tetanus toxoid immunization, days of iron, folic acid & calcium supplementations all were found to be not significantly associated with low birth weight. Conclusion: Women residing in rural areas, women with unfavourable outcome of previous pregnancy and women with any morbid condition during present pregnancy need special attention as these conditions were found to be significantly associated with LBW.