Abstract: Low birth weight (LBW) is one of the major challenges in achievement of the Millennium Development Goals particularly in low and middle-income countries, the incidence in India being reported to be around 28 percent. The risk of a poor outcome in the LBW infants is increased in a background of poor nutrition, both of the mother and the infant. Recent estimates suggest that stunting, wasting, and intrauterine growth restriction are responsible for 2.2 million deaths and 21% of disability-adjusted life years lost among children younger than 5 years [1]. The LBW infant is faced with rapid rate of anabolic processes and brain growth but has poor reserves. Thus the infant’s need for optimal nutrition and special care is critical. Deficient nutrition and improper care lead to fatal outcome. LBW is universally the single most important determinant of the chance of newborn to survive and experience healthy growth and development. LBW as a health indicator is very sensitive to socio-economic factors, in particular to adverse conditions such as hunger, draught, infections and physical stress which specifically affect the poorest segment of population. Determinants of LBW need to be studied in order to identify potentially modifiable risk factors. This brief review explores the available epidemiologic data to investigate the questions of what are the causes and consequences of LBW.