The 2015 Asia-Pacific Association for the Study of Liver Diseases (APASL) Annual Meeting report suggests that the ultimate goal of eradicating hepatitis B virus (HBV) infection will be achieved through vaccination, treatment of patients and interruption of transmission. In China, mother-to-child transmission of HBV is the most important pathway leading to chronic HBV infection, and studies have shown that more than 80% of newborns or infants infected with HBV will become chronically HBV-infected. Therefore, it has been a serious challenge for infectious disease physicians to interrupt and reduce mother-to-child transmission of HBV and achieve “zero infection” of HBV in newborns. Influence of pregnancy on chronic HBV infection During pregnancy, many changes occur in the mother’s body, such as the trophoblast cells of the embryo and the uterine tissues of the mother can increase the synthetic Fas ligand, indoleamine 2,3-dioxygenase, and leukemia inhibitory factor, etc., and the balance of helper T cells (Th cells) tends to be dominated by the response of Th2 cells, and the number of regulatory T lymphocytes (Tregs) is increased, etc., which are can deepen the state of maternal immune tolerance, increase HBV replication, and induce hepatitis activity. However, after the end of pregnancy, the maternal immune tolerance status can be rapidly restored to the pre-pregnancy level or even the phenomenon of reversal-immunity enhancement, and some scholars believe that this change in the immune status before and after pregnancy may be the reason for the abnormalities of liver biochemical indexes in the postpartum period of some chronic HBV-infected patients. Ter Borg et al. showed that 45% of chronically HBV-infected pregnant women had a spontaneous decrease in HBV-DNA levels accompanied by an increase in alanine aminotransferase (ALT) to 3 times or more of the upper limit of normal (ULN) in the first 6 months postpartum. 2 studies by Lin et al. reported that the postpartum HBV e antigen (HBeAg) and conversion rates of HBV e antigens (HBeAg) of HBV-infected pregnant women in the immune tolerance phase were reported respectively. The spontaneous disappearance and conversion rates were 16.7% and 12.5%, respectively. Another researcher selected 30 HBV-carrying pregnant women with tibivudine (LdT) intervention in late pregnancy, who had postpartum ALT ≥2×ULN with decreased levels of HBV-DNA and HBeAg, and applied antiviral treatment with pegylated interferon in combination with adefovir for 96 weeks, and 93.3% of the patients achieved virologic response. This suggests that we should pay attention to the possible influence of pregnancy status on chronic HBV infection, and choose the appropriate timing and method of antiviral treatment to achieve the benefit of both mother and baby. Impact of chronic HBV infection on mother and child Maternal chronic hepatitis B (CHB) activity can lead to an increase in maternal and infant complications, seriously jeopardizing the health of mothers and infants, mainly in two aspects: first, the mother’s combined liver biochemical indexes abnormality, so that the rate of post-partum hemorrhage, puerperal infections, low-body-mass babies, intrauterine distress, preterm labor, stillbirth, neonatal asphyxia is obviously increased, and the results of the existing studies show that chronic HBV infection is associated with gestational diabetes mellitus, antepartum hemorrhage, preterm labor, and decreased neonatal Apgar score (which evaluates the condition of the newborn and the effectiveness of resuscitation). Secondly, during pregnancy, maternal metabolism is enhanced and the burden on the liver is heavy, and CHB occurring during this period is prone to develop into liver failure with complications of multi-organ failure, which can jeopardize the life of the mother and child. Therefore, management of chronically HBV-infected women of childbearing age and interruption of mother-to-child transmission is the source of prevention and treatment of hepatitis B and related diseases. Application of antiviral drugs during pregnancy in women of childbearing age Although APASL and European Society of Hepatology guidelines for hepatitis B suggest that interferon therapy is preferred for chronic HBV-infected women of childbearing age before pregnancy, but they cannot conceive during interferon therapy; if antiviral therapy is required during pregnancy, pregnancy B drugs can be chosen; if the purpose of treatment is to block mother-to-child vertical transmission, HBV-DNA can be chosen when HBV-DNA is >106IU/ml. If the purpose of treatment is to prevent mother-to-child transmission, LdT or tenofovir (TDF) can be chosen when HBV-DNA is >106IU/ml. However, there are still some clinical controversies about antiviral treatment in pregnancy, and most scholars agree to categorize pregnant women with chronic HBV infection into the following situations. 1, high viral load immunotolerant patients: the higher the HBV-DNA level of pregnant women with chronic HBV infection, the higher the incidence of perinatal transmission. 10-15% of newborns of pregnant women with HBV-DNA>107IU/ml still have a mother-to-child blockage failure rate after combined immunization. for these pregnant women with high viral load but normal liver biochemical indexes, the indication for drug administration is to block mother-to-child transmission and reduce chronic infection in newborns. In these high viral load but normal liver biochemistry pregnant women, the indications for drug administration are to interrupt mother-to-child transmission, reduce chronic neonatal infection, and prevent fluctuations in liver biochemistry during pregnancy. Some researchers suggested that for those with HBV-DNA >107 IU/ml or a history of HBV-positive infants with HBV-DNA >106 IU/ml, oral antiviral therapy with pregnancy category B drugs should be given at the 28th week of pregnancy and continued until 1 month postpartum for evaluation of the condition and then a decision should be made whether to discontinue the drug or to continue the treatment. Liver biochemistry and HBV-DNA were measured at 1, 3 and 6 months after discontinuation of the drug, and the patient was followed up until 1 year after delivery. Otherwise, antiviral treatment may be withheld. China’s Guidelines for the Prevention and Control of Chronic Hepatitis B (2015 edition) (hereinafter referred to as the Guidelines) suggests that if HBV-DNA is detected to be >106 IU/ml in the middle and late stages of pregnancy, after fully communicating with the patient and weighing the advantages and disadvantages, TDF, LdT, or lamivudine (LAM) can be given starting from the 24th to the 28th week of pregnancy, and it is recommended that the drug be discontinued 1-3 months postpartum, and that after discontinuation of the drug it can be Breastfeeding is allowed. It must be noted that all HBsAg-positive pregnant women should be monitored for ALT and HBV-DNA at 1, 3, and 6 months postpartum, and if hepatitis activity occurs, appropriate treatment should be administered according to the hepatitis B control guidelines, and the mother should be observed for seroclearance and conversion of HBeAg or conversion to anti-HBe. All newborns should be standardized for active-passive combined immunization, and blood should be drawn at birth and 7 months of age for infant HBV serological markers and HBV-DNA. 2. Chronic Hepatitis B Activity Occurred During Pregnancy: For pregnant women with CHB activity during pregnancy, the Guidelines point out that, if the patient’s ALT is mildly elevated can be closely observed; for those with more severe liver lesions, after fully communicating with the patient and weighing the advantages and disadvantages, they can be use TDF or LdT antiviral therapy. Some scholars specifically suggested that if baseline HBV DNA >105~106IU/ml, ALT >2×ULN or obvious liver fibrosis, it is recommended that antiviral treatment should be carried out as far as possible in the second or third trimester of pregnancy after systematic B-mode ultrasound screening; in principle, antiviral treatment is not recommended in the early stage of pregnancy, and active antiviral treatment is recommended in any stage of pregnancy if liver function continues to deteriorate during pregnancy; meanwhile Monitoring is performed during pregnancy and postpartum, and the efficacy is evaluated 1 month after delivery, and the continuation of treatment is determined according to the treatment roadmap. If baseline HBV DNA is <105 IU/ml and liver biochemical parameters are mildly abnormal, strict pregnancy monitoring is performed. The antiviral treatment of pregnant women with active hepatitis during pregnancy can normalize ALT and effectively reduce the incidence of infant infection.Pan et al. treated 53 cases of chronic hepatitis B patients with active HBV DNA＞106IU/ml during pregnancy with LdT, and 35 cases in the control group, with the liver biochemistry indexes normalized at 92% to 71% before delivery, and the infection rate of the infants at 7 months of age was 0 to 8.6%.3, chronic hepatitis B patients with active hepatitis B at baseline HBV DNA＜105IU/ml, were strictly monitored during pregnancy. 3, pregnancy in patients with chronic hepatitis B: women with CHB should plan their pregnancy, and baseline assessment of HBsAg, HBeAg, anti-HBe, HBV DNA, severity of liver disease, and whether there is a combination of other viral infections should be performed before pregnancy. The tolerance of pregnancy and the risk of mother-to-child transmission are assessed, and reproductive function is examined and evaluated. The goals of treatment for CHB in pregnancy are: stable liver biochemistry in the mother during pregnancy and no HBV infection in the newborn.The mother needs to be monitored regularly throughout pregnancy for liver biochemistry, HBV DNA level, to assess whether the mother has progressed liver disease and whether antiviral therapy is needed. If the baseline HBV DNA level is low (HBV-DNA <106 IU/ml in HBeAg-positive individuals; HBV-DNA <105 IU/ml in HBeAg-negative individuals) and there is no significant fibrosis, antiviral therapy is withheld and monitored during pregnancy. If repeat HBV-DNA is >105-106IU/ml in the second trimester of pregnancy with persistent abnormal liver biochemical parameters, antiviral therapy should be given. If the patient has a high baseline HBV DNA level, ALT > 2 × ULN or significant hepatic fibrosis, antiviral therapy and monitoring during pregnancy are recommended. If the patient has cirrhosis before pregnancy, patients with decompensated cirrhosis should be fully evaluated in specialized hospitals, and pregnancy is generally not suitable; compensated cirrhosis is recommended to be treated with antiviral therapy prior to pregnancy with LdT, TDF or LAM, and then pregnancy after stabilization of the condition, and the antiviral treatment with the above drugs should be continued during pregnancy, and the patient should be monitored throughout the pregnancy, and the treatment should be continued postpartum and managed according to the guidelines for internal liver disease. Management should be carried out according to the guidelines of internal medicine liver disease. Pregnancy during antiviral therapy for patients with chronic hepatitis B: For women who want to get pregnant during antiviral therapy, the treatment should be individualized according to the specific situation. Firstly, for patients who are going to be pregnant, it is necessary to assess whether the patient has reached the indication of drug withdrawal, and HBV DNA and ALT levels should be monitored in the whole process after drug withdrawal, and the decision of antiviral treatment or not should be made according to the specific situation after pregnancy. This applies to patients with mild hepatitis who have reached the indication for discontinuation, and patients who have serious rebound or less likelihood of disease progression. Secondly, for women who are unexpectedly pregnant during antiviral treatment, the Guidelines recommend that: ① pregnancy during antiviral treatment with pregnancy B drugs or LAM can be informed of the risks involved and continue the pregnancy; ② pregnancy during treatment with other NAs can choose to immediately change to pregnancy B drugs to continue the pregnancy or terminate the pregnancy; ③ pregnancy during interferon treatment, it is recommended to terminate the pregnancy, and after six months of interferon withdrawal Then consider pregnancy, drug resistance monitoring in the course of antiviral therapy.