Pregnancy is the main determinant of some liver diseases in humans: acute fatty liver of pregnancy, cholestasis of pregnancy, and acute liver failure in toxaemia of pregnancy. Pregnancy also modifies the natural history of other more common hepatobiliary diseases, such as cholesterol gallstones. Sex hormones (mainly oestrogens, progesterone and/or some of its metabolites) and prolactin are considered responsible for these pathological consequences and they also appear to be influential in the outcome of several other hepatobiliary disorders, in both sexes and all ages. Although these...