Western diets are characterized by a plethoric, hypercaloric diet containing more and more processed foods, combining overnutrition in lipids and qualitative imbalance in fatty acids. The objective of our work was to evaluate, in a rabbit model, the effects of a high-fat diet (H, enriched in soybean oil and cholesterol) on the maternal phenotype and on the development and health of the offspring. Embryo transfers were used to determine the window(s) of vulnerability linked to this exposure. In mothers, diet H induced dyslipidemia, aortic atherosclerosis and follicular atresia. From the 8–16 cell stage, the H embryonic phenotype was disrupted and the blastocyst stage was characterized by a trophoblastic accumulation of lipid globules. Later in gestation, the fetuses were hypotrophic and dyslipidemic. Transplacental exchanges were affected, with sex-specific effects. The adults showed symptoms of metabolic syndrome. Reproduction was disrupted in both sexes. Embryo transfers have made it possible to show the preponderant role of the maternal gestational diet on the feto-placental phenotype while undeniably demonstrating pre-conception programming. These two periods could therefore be windows of intervention to limit the fetal and placental consequences of a nutritional imbalance.