Background and aims – Excess caloric load or a proinflammatory diet may contribute to gut barrier dysfunction, leading to increased nutrient uptake and components of the microbiota passing into the systemic circulation. These effects have been linked to the development of obesity and the metabolic syndrome (1,2). As the maternal diet has been shown to have a significant effect on offspring development (3), we used a porcine model of a fat supplemented diet to test the effect of maternal diet on offspring gut development at two timepoints. Materials and methods – 16 sows were randomly assigned (n=8 per group) to a control diet of commercial feed (maternal control, mC) or commercial feed supplemented with palm oil (maternal high fat, mHF) from the first day of breeding, and continued with a gradually increasing amount of palm oil throughout gestation. Diets were made isocaloric by reducing the starch content in the palm oil supplemented diet. Sows farrowed naturally and their offspring were fed standard commercial diets regardless of maternal diet. All offspring were grouped based on diet and size at birth. The first group were dissected at 7 days (mC median n=6, mC small n=7, mHF median n=8, mHF small n=7), and the second at 6 months (mC median n=6, mC small n=4, mHF median n=6, mHF small n=5). Three genes coding for proteins located on epithelial tight junctions were used as markers of gut barrier function: claudin-3 (CLDN3), occludin (OCLN), and zonulin-1 (ZO-1). Epidermal growth factor receptor (EGFr) was used as a marker of intestinal development. Quantitative PCR was used to measure mRNA abundance of the above genes in RNA extracted from the ileum. All data is presented as mean±SEM, with groups compared using Student’s t-test or Mann-Whitney U test as appropriate. Results – Birth weight and small intestine weight relative to total body weight were unaffected by maternal diet at both timepoints. Expression of CLDN3 and OCLN was significantly reduced in mHF median offspring at 7 days compared to mC median, EGFr was significantly reduced in both mC small and mHF median offspring compared to mC median at 7 days (see figure). ZO-1 expression at 7 days was unaffected by diet or size. Expression of all four genes was not significantly different between groups at 6 months. Conclusion – These findings demonstrate a high-fat diet during pregnancy may increase intestinal permeability in the offspring, and adversely affect intestinal development at an early age. However the changes observed at 7 days are no longer present in 6 month old pigs, suggesting that development of the small intestine taking place after 7 days, predominantly at weaning (4) may compensate for any adverse effects. Further work will explore whether other organs such as the liver are adversely affected by an increased intestinal permeability at 7 days.