 Intrahepatic Cholestasis of Pregnancy, ICP, is a liver disease that sometimes develops during pregnancy and is characterized by increased serum bile acid levels. Here the authors report that the gut microbiome species B. Fragilis is enriched in patients with ICP and promotes ICP development in mice via inhibition of signaling, though the bile acid receptor FXR. This article was authored by Botang, Lytang, Chimpingli, and others.