The Western dietary pattern, characterized by high consumption of fats and sugars, has been strongly associated with an increased risk of developing Crohn's disease (CD). However, the potential impact of maternal obesity or prenatal exposure to a Western diet on offspring's susceptibility to CD remains unclear. Herein, we investigated the effects and underlying mechanisms of a maternal high-fat/high-sugar Western-style diet (WD) on offspring's susceptibility to 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced Crohn's-like colitis.Maternal dams were fed either a WD or a normal control diet (ND) for eight weeks prior to mating and continued throughout gestation and lactation. Post-weaning, the offspring were subjected to WD and ND to create four groups: ND-born offspring fed a normal diet (N-N) or Western diet (N-W), and WD-born offspring fed a normal (W-N) or Western diet (W-W). At eight weeks of age, they were administered TNBS to induce a CD model.Our findings revealed that the W-N group exhibited more severe intestinal inflammation than the N-N group, as demonstrated by a lower survival rate, increased weight loss, and a shorter colon length. The W-N group displayed a significant increase in Bacteroidetes, which was accompanied by an accumulation of deoxycholic acid (DCA). Further experimentation confirmed an increased generation of DCA in mice colonized with gut microbes from the W-N group. Moreover, DCA administration aggravated TNBS-induced colitis by promoting Gasdermin D (GSDMD)-mediated pyroptosis and IL-1beta (IL-1β) production in macrophages. Importantly, the deletion of GSDMD effectively restrains the effect of DCA on TNBS-induced colitis.Our study demonstrates that a maternal Western-style diet can alter gut microbiota composition and bile acid metabolism in mouse offspring, leading to an increased susceptibility to CD-like colitis. These findings highlight the importance of understanding the long-term consequences of maternal diet on offspring health and may have implications for the prevention and management of Crohn's disease. Video Abstract.© 2023. The Author(s).