Obstetric cholestasis is a liver disorder that affects about one in 200 pregnancies in the UK. It causes pregnant women to itch and is associated with problems for the unborn baby including premature delivery and stillbirth late in pregnancy. It is estimated that obstetric cholestasis currently causes 20 stillbirths and 800 premature deliveries each year in the UK. Affected mothers have abnormal liver tests and raised bile acids in the blood. Raised bile acids have also been reported in 5% of unexplained stillbirths. Stillbirth sadly affects one in 1000 pregnancies, so the effects of cholestasis may extend further than has been previously recognised. This project will study the proteins that control the levels of bile acids in the blood. This will be done firstly using genetic material from a large number of women affected by obstetric cholestasis. Tests will also be performed to find out whether the bile acids produced by the unborn baby (some of which are not normally found in adults) cause the mothers to lose the ability to control bile acid levels in the blood. The team will also study whether pregnancy hormones have an effect. The results should help the development of correct treatments for women with the condition, and help doctors predict and minimise the risk of fatal consequences for the unborn baby.