Atmospheric pollution is a rising concern in urban areas and a major contributor to people's mortality. So far, little is known about the intergenerational effects of in utero exposure. Available studies in rodents indicate that maternal exposure to diesel exhaust (DE) alters male or female reproductive function with decreased daily sperm production, altered steroidogenesis and reclucecl ovarian follicle number. Moreover, continuons exposure of mice to ambient air in Sao Paulo, Brazil, over 3 generations reduced female fertility and induced fetal abortions, fetal growth retardation and altered placental structure. Our aim was to evaluate the effects of exposure of pregnant females to diluted DE on feto-placental development in the second generation. Pregnant female rabbits (FO) were exposed to diluted (lmg/m3) and filtered DE (nanoparticle (NP) diameter "°' 69nm) (E: exposed group) or clean air (C: Control group) for 2h/day, 5days/week by nose-only exposure from 3 to 27 days post-conception (dpc)[l]. Offspring (Fl) were not exposed to DE. Fl females were mated with contral males at adulthood. Second generation (F2) feto-placental units were collected at 28 dpc from Fl females. Fatty acid (FA) profiles (plasma and placenta) were analyzed by gas chromatography and differential profiles between the two groups were cletermined through Principal Component Analysis. Identification of biological pathways enriched in genes associated with grandmother exposure was performed using Gene Set Enrichment Analysis (GSEA) from placental transcriptomic data. At 28 dpc, there was no difference for maternal Fl biochemistry between groups although total hepatic neutral lipid (NL) contents were significantly increased in Fl E females. In placentas (F2), total NL concentration was increased in the E group mostly with monounsaturated fatty acids while arachidonic acid (AA, pro-inflammatory precursor) was proportionally reduced. In fetal plasma (F2), there was an increase in triglycerid and a decrease in total cholesterol concentrations. Moreover, the proportion of n-3 po1yunsaturated fatty acids (n-3 PUFA, precursors of anti-inflammatory molecules) was increased and that of AA decreased in E compared to C. fetal plasma. Using stereological approaches, no structural difference was observed in placentas between groups. Nevertheless, GSEA analyses of transcriptomic data showed that proteasome complex and ubiquitin pathways, involved in protein degradation, were enriched in E versus C placentas. On the opposite, ion channel and inflammation regulation pathways were enriched in C compared to·E· In conclusion, in utero exposure of Fl females to DE can affect placentaL function and fetal metabolism in their F2 offspring. Placental FA profiles suggest adaptive protective mechanisms against inflammation, through the placetal storage of non essential FA and the favored transplar cental transfer of nc3 PUFA. The physiological consequences of observed alterations in placental genes involved in protein metabolism and intracellular signaling remain to be determined. These effects most likely result from altered in utero development of maternal Fl gametes.