The nutritional status of the mother before and during pregnancy has been observed in recent years as one of the most influential environmental factors on fetal development. This study focuses on the early stages of gestation or periconception period: preconception, conception, implantation, embryogenesis and placentation; since they represent a critical step in pregnancy outcomes. After an extensive literature review of 66 studies published between 1990 and 2015, iron, iodine, omega 3 fatty acids, folic acid and other B vitamins, minerals and micronutrients for which more evidence of a positive relationship with the development of the offspring were found. The approach of a dietary intervention by the dietitian, both individually and collectively, in the preconception period in women of childbearing age and/or pregnancy intentions is proposed in this study, being able to continue the intervention in periods of gestation, breastfeeding, postpartum and even offspring, causing long-term benefits, which are likely to remain and manifest throughout an individual’s life.