I. Immunization during pregnancy 1. globulin-like toxins, inactivated vaccines can be used, such as: rabies vaccine, meningitis vaccine, hepatitis B vaccine, influenza vaccine, pneumococcal, tetanus antitoxin, etc. 2. live vaccines are not recommended for use during pregnancy, and are generally used before conception, with the best interval of 3 months before conception, such as measles vaccine, mumps vaccine, chickenpox vaccine, yellow fever vaccine, polio vaccine, rubella vaccine, etc. 2. Issues related to mother-to-child transmission of hepatitis B virus 1. Mother-to-child transmission of hepatitis B virus: The transmission of hepatitis B virus from the previous generation to the next generation is called mother-to-child transmission. (1) intrauterine transmission: intrauterine infection reports vary, some literature reports even up to 40%, the current more authoritative report that the real intrauterine infection < 5%, this mode of transmission is still the lack of effective preventive measures. (2) Intrapartum transmission: caused by the fetus swallowing HBsAg-containing maternal blood, amniotic fluid, vaginal secretions, or maternal blood leaking into the fetal circulation while passing through the birth canal. (3) transmission during childbirth: related to breastfeeding and close contact with the mother, when the mother's blood is positive for HBsAg, HBeAg and anti-HBc (the so-called "triple-positive"), the rate of HBV-DNA in breast milk reaches 100% transmission during childbirth and postpartum transmission is the main mode of vertical transmission, and can be prevented. 2. Issues related to newborns whose mothers are HBsAg negative but whose fathers and other family members are HBsAg positive (1) Although HBV-DNA has been reported to be detectable in semen, there is no evidence that semen can cause chronic HBV infection in the next generation. (2) If the newborn is born mainly under the care of HBV-carrying family members, the newborn should preferably be injected with 100 IU of hepatitis B immunoglobulin in addition to vaccination. 3, HBsAg-positive mothers breastfeeding despite reports that HBsAg and HBV-DNA can be detected in breast milk, but after the newborn takes formal hepatitis B virus immune blockade, the literature reports that breastfeeding does not increase the risk of HBV infection in newborns. 4, the feasibility of using immunoglobulin to prevent intrauterine infection in late pregnancy in hepatitis B carriers (1) Chinese scholars first proposed in 1995 that the use of hepatitis B immunoglobulin in late pregnancy in HBV-carrying pregnant women could prevent intrauterine infection. (2) Method: 200-400 IU of hepatitis B immunoglobulin is injected every 4 weeks starting from 28 weeks of pregnancy and again before delivery (3) Its mechanism is believed that: hepatitis B immunoglobulin can reduce the amount of virus in pregnant women. (4) Question: How can the above usage reduce the viral load when the liver of HBV carriers releases 1010-1012 viruses per day and the HBsAg level in the blood is 1000-100,000 times higher than that of HBV. Subsequent studies have also confirmed that the use of hepatitis B immunoglobulin in late pregnancy has a similar rate of chronic HBV infection as routine post-exposure prophylaxis in infants and children. Therefore, the idea of using hepatitis B immunoglobulin in late pregnancy to prevent intrauterine HBV infection lacks sufficient basis and cannot be applied to practical prevention. 5, the feasibility of using anti-hepatitis B virus treatment during pregnancy (1) many studies have shown that the use of nucleoside antiviral drugs for all periods of pregnancy can effectively reduce serum viral load, the use of therapeutic doses of drugs can reduce the rate of mother-to-child transmission of hepatitis B pregnant women and no significant toxic reactions to the embryo. Representative drug: lamivudine (2) Since lamivudine has not been introduced into antiviral therapy during pregnancy for a long time, its long-term safety has not been reported. 6. Several recommendations for the use of anti-hepatitis B virus therapy (1) It is recommended to use before pregnancy, stop the drug after the patient's viral level is reduced or negative, and conceive 1-3 months after stopping the drug. (2) For pregnant women with very high viral load and abnormal liver function, antiviral therapy is recommended for those whose pregnancy may be difficult to maintain without appropriate treatment. (3) It is not recommended for pregnant women who are viral carriers only but do not have a high viral load. (4) Pregnant women with very high viral load but stable condition and normal liver function may be explained the pros and cons of medication and the indications for antiviral therapy may be appropriately relaxed according to the opinion of the pregnant woman and her family. (5) The timing of antiviral treatment can be based on the condition of the pregnant woman, and the use of drugs in early pregnancy can be avoided as much as possible. (6) Full communication with pregnant women and their families should be made before treatment to achieve informed choice. The safety of imaging examinations during pregnancy 1. Ultrasound examination: Ultrasound examination has become a necessary tool for the diagnosis of many diseases and for the examination of the fetus. At present, there is a consensus in obstetrics and gynecology that ultrasonography, including Doppler, is safe for the fetus during pregnancy and should replace X-ray as the preferred method of fetal imaging as far as possible. X-ray examination: The effect of X-ray examination on the fetus is related to the amount of radiation and the timing of exposure; a large amount of X-ray radiation may cause miscarriage and malformation, but the absorbed dose of medical radiation examination is extremely low; before 2 weeks after fertilization or after 20 weeks, a single X-ray examination will not cause damage to the fetus, therefore, non-essential X-ray examination should be cautious or postponed after 2-20 weeks after fertilization. MRI: The effect of MRI on the fetus is still unclear, although most studies have shown no effect on the development of animal embryos, a few studies have suggested that exposure to the magnetic field of MRI in early pregnancy may have a teratogenic effect on animal fetuses. Therefore, this test should still be performed with caution in early pregnancy and should only be used in women in early pregnancy when the test is relevant to decisions about the management of the disease. MRI is safe for fetuses in mid- to late-term pregnancies. 4.Other: 1.Radionuclides or radiopharmaceuticals: Unlike X-rays and MRI, the former will remain in the body for a period of time, therefore, women who have received radionuclide tests should avoid pregnancy for a certain period of time, depending on the type of radionuclide. 2. Electric blankets, microwave ovens, television, cell phones and computers: There is no evidence of harmful effects on the fetus.