Pregnancy induces many physiological changes, some of which may have pathological results. In population studies, gallstones were found in 6.5% to 8.4% of nulliparous women, and in 18.4% to 19.3% of women with two to three or more pregnancies. In women followed throughout pregnancy, neoformation of gallstones was documented in 3% to 8.1% depending on the population. Some 20% to 30% of these gallstones redissolve postpartum. The frequency of biliary colic during pregnancy is controversial, and the recommended therapeutic approach during pregnancy is conservative. When essential, invasive procedures are relatively well tolerated, preferably during the second trimester. Biliary sludge disappears postpartum in the great majority. Gallstones and sludge are most likely caused by biliary stasis, prolonged intestinal transit and increased cholesterol saturation of bile, which were all demonstrated to occur during pregnancy.