Background:We describe the evidence of the effects of early life exposures on health and aging during adulthood. Methods: A narrative review of cohorts and systematic reviews of studies initiated early in life and followed up to adulthood was conducted. Results: Most studies were carried out in developed countries. The long-term effects of birth weight and, to a lesser extent, height at birth on chronic-degenerative diseases, functionality, bone, renal and respiratory pathology, and mortality have been consistent. Breastfeeding is associated with metabolic and cardiovascular diseases and functionality. Adiposity, bone pathophysiology, functionality in old age, and high blood pressure are associated with socioeconomic status at birth. Conclusions: Several exposures from intrauterine life to adolescence that exert discrete but significant effects on adult health have been consistently described. It is necessary to carry out these studies in developing countries.