Low-birth-weight (LBW) infants have a significantly greater mortality than other babies, not only within the neonatal period but also in infancy and early childhood. Babies are LBW either because they are preterm or they have experienced intrauterine growth retardation. Reducing the prevalence of LBW babies is important in reducing child and infant mortality. Risk factors for prematurity and intrauterine growth retardation are well established. Socioeconomic conditions and nutrition during pregnancy are two key factors. Interventions to reduce the prevalence of LBW infants in developed countries have usually been unsuccessful. A few studies in developing countries have, however, achieved positive results. Cuba has managed to reduce the prevalence of LBW infants and their model of healthcare in relation to achieving this is described. Key features of the Cuban healthcare system are that it is both free and universal, and additionally there is a strong emphasis on primary healthcare. It is likely that a similar approach in both developing countries and disadvantaged communities in developed countries would reduce the prevalence of LBW babies. This would have a major impact in relation to reducing infant mortality rates.