Comprehensive review of telbivudine in pregnant women with chronic hepatitis B

Table 1 Food and drug administration pregnancy categories for hepatitis B virus antiviral therapy[15]

Pregnancy category	definition	HBV therapy categorization
A	Adequate and well controlled studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters)	None
B	Animal reproduction studies have failed to demonstrate a risk to the fetus, and there are no adequate and well-controlled studies in pregnant women or animal studies that have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester	Telbivudine; Tenofovir
C	Animal reproduction studies have shown an adverse effect on the fetus, and there are no adequate and well controlled studies in humans, but potential benefits might warrant use of the drug in pregnant women despite potential risks	Lamivudine; Entecavir; Adefovir
D	There is positive evidence of human fetus risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits might warrant use of the drug in pregnant women despite potential risks	None
X	Studies in animals or humans have demonstrated fetus abnormalities, and/or there is positive evidence of human fetus risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits	Interferon