Obstetric cholestasis (OC) is a liver disorder that occurs during pregnancy. Sometimes referred to as intrahepatic cholestasis of pregnancy (ICP), it is a condition in which the flow of bile from the liver is reduced. This causes affected women to have an increase of chemicals, known as raised bile salts, in their blood.
OC is characterised by itching, known as pruritus. The itching generally appears in the last three months of pregnancy but can appear sooner. It is of variable severity and can be extremely distressing for the mother. It completely disappears soon after birth and does not cause long-term
health problems for mothers.
Several fetal complications have been reported in OC pregnancies. Recent studies suggest that women with raised levels of bile salts in the blood have increased risks of preterm delivery and fetal distress. Some case studies have also reported stillbirth occurring near the end of pregnancy in women with OC. Therefore it is essential that the condition is recognised and treated in time.
Most obstetricians in the UK aim to deliver early, at around 37 or 38 weeks. This is done to help prevent the possibility of stillbirth.
Doctors do not yet know what restricts the flow of bile from the liver in OC.
One theory is that your liver cannot cope with the high levels of hormones associated with pregnancy (estrogen and progesterone). This leads to a reduction in the flow of bile and causes a build up of bile salts in the blood. This is believed to be what causes itching in the mother and can lead to jaundice (a yellowing of the skin and the whites of the eyes) in a small number of OC cases. The transfer of bile salts across the placenta is thought to contribute to the risk of the baby dying in the womb.
There is also a theory that OC has a genetic cause. This means it is linked to an abnormality or ‘mutation’ in a gene or genes. While mutations that may be linked to OC have been identified, they do not currently explain all the causes of the disorder and further research is being carried out.
There have been no reports of any harmful effects to babies born to mothers who have had OC once they have been delivered. Large follow-up studies have not yet been carried out.
How common is OC?
OC may affect up to 1% of the population and is more common in twin and triplet pregnancies. The number affected among South Asian women is slightly increased (1.5%) and much higher still in South American countries and in Scandinavia (over 2%). This is seen by some to support evidence that suggests OC has a genetic or environmental cause.