Background: Low birth-weight in infants is further categorized as Extreme low-birth weight (ELBW), Very low-birth weight (VLBW) and Low-birth weight (LBW) when weight at birth is <1 kg, ≥ 1 kg to <1.5 kg and ≥ 1.5 kg to <2.5 kg respectively. It is not clear how these various categories predict co-morbidities, duration of hospital stay and survival in affected newborns. Identifying such relationships will help prioritization of care, and this study is designed to explore these. Methods: This is a prospective study conducted over a 45 months period at the neonatal intensive care unit (NICU) of the Enugu State University Teaching Hospital (ESUTH), Enugu, Nigeria. Results: A total of 167 LBW newborns were enrolled, with about 90% born preterm. ELBWs constituted 20 (12.0%), while 47 (28.1%) and 100 (59.9%) were VLBW and LBW respectively. About 50 (32%) of the babies did not survive. Of these number, 16/20 (80%) were ELBW babies, 19/47 (41%) were VLBW while 15/91 (17%) were LBW babies, (P=0.001). Survival analysis showed that ELBW HR 20.27; P=0.001] and VLBW [HR 3.57; P=0.002] babies were respectively about 20 and 4 times more likely to die relative to the LBW group. Recurrent apnoea and the need for respiratory support were significantly more common among ELBWs and VLBWs relative to LBWs (P=0.001), while the LBW babies developed less hypothermia but more hypoglycemia (P=0.001). No significant differences were observed in the incidences of other co-morbidities. Conclusion: We conclude that low mean weights in infants are associated with higher fatal outcomes and prolonged hospital stays as well as a number of co-morbidities.