Many pregnancies are complicated by a pruritus. A study of the liver functions, including a determination of plasma bile acids, and a biopsy of each doubtful dermatological lesion with direct immunofluorescence allow to distinguish the specific pruritic diseases of the pregnancy: pemphigoid gestationis, papulous and pruritic dermatitis and cholestasis of pregnancy. The pemphigoid gestationis is an autoimmune bullous acquired dermatosis, which recurs at each pregnancy; a positive direct immunofluorescence is specific of the disease; the fetal prognosis seems to be good; a systemic corticotherapy is necessary. The papulous and pruritic dermatitis are the most common dermatosis during the gestation: the maternal and fetal prognosis are excellent, but this diagnosis remains a diagnosis of elimination. The cholestasis of pregnancy is characterized by an isolated pruritus which rapidly disappears in the postpartum period; its pathogeny probably includes many factors, but it seems to be favoured by a genetic ground; the determination of plasma bile acid, even if it is not specific, leads toward the diagnosis. The mother often requires an aggressive symptomatic treatment but the delivery can be delayed till the pulmonary maturity is obtained.