Understanding the issues surrounding the impact of environments and interactions during the first 1,000 days is crucial for developing a health promotion strategy for this period. Factors related to life experiences, living conditions, and interactions will have a decisive impact on the body and its ability to adapt over time. Prevention and health promotion strategies during the first 1,000 days must take into account this scientific knowledge and the new perspectives it offers. This calls for adapting approaches to provide parents and prospective parents—and, more broadly, the general population—with useful information and appropriate, proportionate interventions to reduce the impact of vulnerabilities on children’s healthy development. The body of available knowledge offers a new perspective on the perinatal experience as a determinant of the health of the developing individual at all stages of life.