Climate changes and increasing temperatures is going to increase the incidence for fetal programming in sheep. Recognizing the importance of in utero nutrition might help to sustain small ruminant production in the future. The adverse impact of fetal programming for performance in lambs have already been assessed, and expandability of the subcutaneous adipose has earlier been found to be a main target of fetal programming, causing metabolic dysfunction. The aim of this study was to clarify the importance of in utero nutrition in animal nutrition science by investigating the long-term effect of fetal programming on performance in adult sheep and to investigate whether the subcutaneous adipose tissue was still a main target. Body measurements, carcass characteristics, the subcutaneous adipose tissue and plasma metabolites were analyzed in 2½ year old sheep exposed to either prenatal under- (LOW) or overnutrition (HIGH) or adequately fed (NORM) and subsequently exposed to early postnatal diets until 6 months of age: either a high carbohydrate-high fat (HCHF) or conventional diet (CONV). The major findings were that there was a long-term effect of the prenatal diet into adulthood, irrespective of an adverse early postnatal diet. An effect of the early postnatal diet was still evident even after a dietary correction later in life, and a mismatched pre- and postnatal diet also turned out to have long lasting effects. The subcutaneous adipose tissue was still a target of fetal programming, though no longer by impaired expandability, but by an up-regulation of VEGF-A expression. More knowledge is required on the specific critical periods during gestation where productivity can be affected and about the transgenerational effect of fetal programming in sheep and from there, in utero nutrition can become a tool to optimize sheep production in the future.