Table 5. Primary biliary cirrhosis and primary sclerosing cholangitis in pregnancy: medication safety considerations.

US FDA category	Definition	Medications
A	Controlled studies in pregnant women fail to demonstrate fetal risk in the first trimester, or animal reproduction studies fail to demonstrate fetal risk. Possibility of fetal harm appears remote.
B	Animal studies do not indicate fetal risk and there are no adequate well-controlled studies in pregnant women, or animal studies have demonstrated adverse effect but controlled studies in pregnant women have failed to demonstrate risk. Possibility of fetal harm appears remote, but drug should only be used in pregnancy if clearly indicated.	Ursodeoxycholic Acid Octreotide Vasopressin
C	Animal reproduction studies indicate fetal risk, and there are no adequate well-controlled studies in pregnant women. Benefit of medication may be acceptable despite potential risk. Drug should only be used in pregnancy if clearly indicated.	Propranolol
D	Evidence of fetal risk exists based on data from human studies or from investigational/marketing data recorded in humans. Medication benefit may be acceptable despite risk. Drug should only be used in pregnancy if clearly indicated.
X	Definite fetal risk based on animal or human studies or based on human experience. Medication risk clearly outweighs any possible benefit. Drug is contraindicated in pregnancy.

Abbreviation: US FDA (United States Food and Drug Administration).

Reference: http://www.regulations.gov/#!documentDetail;D=FDA-2006-N-0515