Pregnant women are advised by their doctors whether to take tenofovir fumarate, a drug for hepatitis B that reduces the amount of virus, during pregnancy. In medical terms it is a pregnancy class B drug, no clear toxicity has been found, it is a relatively safe drug. If the drug is used frequently during pregnancy, it can have an impact on the body or fetal malformations can occur. The chances of malformation are also higher. Consult your doctor before taking the drug and do not take the drug blindly, the potential danger is unpredictable. It is recommended that pregnant women use less medication during pregnancy, pay more attention to rest, and go to the hospital for examination and medical treatment when symptoms of disease appear to avoid more serious diseases.