Intrahepatic Cholestasis of Pregnancy:Mechanism and Impacts in Pregnancy and Fetal Outcomes

Intrahepatic cholestasis of pregnancy is characterized with unexplained pruritus,elevated concentration of total bile acid and liver transaminases,which are influenced by abnormal hormone level in the second or third trimester,gene mutation,immune injury and increased release of pruritogens.Although it has good prognosis on pregnant women,it plays an important role on increased risk of adverse fetal outcomes,including preterm delivery,fetal distress,fetal mortality and neonatal respiratory distress syndrome.The abnormal metabolism of steroids and elevated total bile acid increase myometrial sensitivity for oxytocin and promote cervical ripening so as to induce premature delivery.Bile acid desposition in the placenta leads to spasm of placental villous vessels and decreasing placental reserve capacity.Also,bile acid accumulation can play a toxin role on fetal heart and lung,resulting in cardiac conduction dysfunction and reduced synthesis of pulmonary surfactant.All these contribute to increased rate of fetal distress,fetal death and neonatal lung injury.