TAF in Early/Middle Pregnancy With CHB

Inclusion Criteria: * Between the ages of 20 and 40 * HBsAg positive for \>= 6 months * 0-24 week of pregnancy * Meets the indications for antiviral therapy in the 2022 version of the guidelines for the prevention and treatment of chronic hepatitis B * It is planned to use TAF or TDF antiviral therapy until the end of delivery or long-term administration, and follow-up will be carried out in this research institution * Signed informed consent for medication Exclusion Criteria: * Previous use of anti-hepatitis B virus drugs (e.g., entecavir, tenofovir, tenofovir alafenol, emintenofovir, adefovir dipoproxil, telbivudine, etc.) * Concomitant viral hepatitis A, C, E or other hepatotropic virus infection or AIDS * Concomitant cirrhosis, liver cancer or other chronic liver diseases (e.g., alcoholic liver, autoimmune liver disease, G6PD deficiency, etc.) * Patients with heart (such as coronary heart disease, myocardial infarction, heart failure, etc.), lung (such as: lung cancer, chronic obstructive pulmonary disease, tuberculosis, etc.), kidney (such as: renal failure, elevated creatinine, nephritis, nephrotic syndrome, etc.) and other important organ diseases * Chronic diseases such as autoimmune diseases (such as systemic lupus erythematosus, rheumatoid arthritis, anticoagulant antibody syndrome), hypertension, diabetes, thyroid disease, etc * Patients with previous pregnancy complications (such as: gestational hypertension, gestational diabetes, gestational eclampsia, etc.) * Those who have had fetal or neonatal growth and development defects in previous pregnancies * Previous or ongoing use of nephrotoxic medications, glucocorticoids, nonsteroidal anti-inflammatory drugs, cytotoxic drugs, or immunomodulators * Premedication ultrasound showed fetal malformations, fetal development abnormalities, placental abnormalities, threatened abortion, etc