As a consequence, the interest of scientists and policy makers is now focused on characterizing the optimal dietary patterns and patterns of prenatal and postnatal size/growth. The objectives of this paper were to briefly review/summarize: (1) evidence of the importance of size and growth as well as early nutrition for health and development, (2) methodological issues associated with current scientific approaches that evaluate the impact of early nutrition/growth on later outcomes, (3) recent regulations and guidelines developed by various expert groups or scientific organizations, and (4) ways to solve some unresolved issues.