This is a pilot study aimed at comparing the effect of metformin versus ursodeoxycholic acid in women with intrahepatic cholestasis in pregnancy. The study will be conducted in three NHS hospital sites, over an 18 month period.

Intrahepatic cholestasis is a condition that affects pregnant women. It is characterised by itching, usually in the third trimester of pregnancy and is associated with an increase in the liver enzymes and bile salts. This can be associated with maternal and neonatal morbidity, and rarely perinatal mortality.

The investigators propose to assess and compare the effect of Metformin versus Ursodeoxycholic acid on lowering liver enzymes and bile salts, improving maternal morbidity and improving neonatal outcomes.

This study is a pilot study that will be conducted at 3 NHS hospital sites where patients will randomly assigned to receive either Metformin or Ursodeoxycholic acid. There will be 20 patient in each arm. Recruitment will commence in February 2017 and will run for an 18 month period.

Inclusion Criteria:

1. 20+0 to 40 weeks' gestation on day of randomisation
2. Itching with a raised serum bile acid above the upper limit of normal
3. Normal anomaly scan at 20 weeks
4. Aged 18 years or over
5. Able to give written informed consent
6. No known pre-existing liver disease

Exclusion Criteria:

1. Decision already made for delivery within the next 48 hours
2. Known allergy to any component of the ursodeoxycholic acid or metformin tablets
3. Patients already on metformin for other conditions