MATERIALS AND METHODS Women with ICP were identified either by the clinicians responsible for their care or by the UK Obstetric Cholestasis Patient Organisation (OCPO). The diagnostic criteria for ICP were met if women had persistent pruritus and biochemical confirmation of the diagnosis in the absence of other known liver disease (including pre-eclampsia with abnormal liver function, the HELLP syndrome, acute fatty liver of pregnancy, primary biliary cirrhosis, and ultrasound abnormality that could result in biliary obstruction). Women were excluded from the analysis if the hepatic impairment did not resolve postnatally, with the exception of cyclical and exogenous oestrogen induced cholestasis. Women with dermatoses of pregnancy that can result in pruritus were also excluded. Abnormal liver function was defined as one or more of raised serum bile acids and/or raised serum transaminases (alanine aminotranferase (ALT), aspartate aminotransferase (AST) or GGT) in at least one pregnancy. As hospitals have different