Currently, it is well established that consequences of prenatal nutritional programming are influenced both by the timing, degree and duration of the challenge and by the adaptive response of the mother and the conceptus. However, the most recent studies suggest that the adaptive responses of the foetuses are also strongly modulated by their sex. Hence, females, which are more critical for the survival of the species, would have better survival and developmental traits than males. Most of the data are based in studies performed in rodents, but evidences in large mammals and humans are elusive. Pigs are a reliable large animal model for translational research in intrauterine growth retardation (IUGR) and subsequent prenatal programming. We are working with a swine model, the Iberian pig, which is characterized by the development of a thrifty genotype with effects on food intake, body weight and fat deposition; Iberian pigs become obese in case of food excess. The IUGR offspring have compromised health status and reduced growth potential in both Iberian and lean commercial breeds. These effects are similar in males and females from lean breeds, but the Iberian pigs have a clear sexual dimorphism. The Iberian males affected by nutritional restriction have reduced growth potential like the offspring from lean swine breeds; IUGR in Iberian males cannot be compensated during postnatal growth. Conversely, Iberian females show an early-postnatal catch-up growth, as early as during lactation, and weight and size are compensated at weaning. Such sex-related differences in early-postnatal developmental patterns may be caused by sex-related prenatal differences in developmental and metabolic traits between male and female Iberian foetuses exposed to prenatal programming. These differences are not found in foetuses from lean breeds, confirming a genotype-related effect which would favour the development of female Iberian offspring in case of environmental