Hepatitis B and Maternal and Infant Safety
Hepatitis B virus can be transmitted through the blood and placenta, and from the birth canal during maternal delivery. In the United States, approximately 3,500 infants become hepatitis B carriers each year. The hepatitis B virus causes large livers in infants with a variety of clinical or subclinical signs, and 25% of these infants often die of cirrhosis and liver cancer by the time they reach adulthood.
China has a high prevalence of hepatitis B. At least 50-60 million women are carriers of the hepatitis B virus. Screening pregnant women for hepatitis B virus indicators, or pregnant women taking the initiative to check hepatitis B virus indicators to detect carriers, so that their newborns can receive vaccine and high-value immunoglobulin injections within 24 hours of birth, and then booster injections with hepatitis B vaccine one month and six months later, can make at least 80%-90% of infants immune to hepatitis B. Therefore, screening of hepatitis B virus indicators in pregnant women is beneficial for eugenics and has the significance of benefiting future generations.
At least 1/3 of chronic HBV carriers are caused by mother-to-child transmission, and currently mother-to-child transmission is the most important route of HBV transmission. The current HBV infection rate among women of childbearing age in China is still as high as 8.16% (7.18% for the general population), with about 1.7 million people. Hepatitis B virus surface antigen (HBsAg) positive pregnant women, their newborns about 40% can be infected, if HBsAg, hepatitis B virus e antigen (HBeAg) are positive, the chance of their newborns infected with HBV can be more than 90%.
On the contrary, if the hepatitis B virus e antibody (anti-HBe) positive, HBsAg negative, HBVDNA negative or low level, HBsAg low titer, the chance of newborns being infected is relatively small, about 10% to 15%.
Routes of mother-to-child transmission of HBV.
1, intrauterine infection, accounting for about 10%, HBV can cause intrauterine infection of the fetus through the placental barrier, the detection rate of HBV infection markers in the liver or blood of induced fetuses up to 40%;
2, the transmission during childbirth, accounting for about 80%. During delivery, the newborn is exposed to or swallowed blood, amniotic fluid or secretions containing HBV through the birth canal;
3, postnatal transmission, accounting for about 10%. After birth through contact with the mother’s saliva, breastfeeding and other close contact in life and spread.
When a pregnant woman is positive for HBsAg, regardless of her HBVDNA level or even “negative”, her newborn will have the possibility of infection if she does not take immunoprophylaxis. About 90% to 95% of newborns infected with HBV through mother-to-child transmission will develop chronic hepatitis, and 20% to 25% of these patients will progress to cirrhosis or even liver cancer. Therefore, the interruption of mother-to-child transmission is very important.
Pregnancy and hepatitis B interact with each other
Pregnancy can increase the burden on the liver: a series of physiological changes occur in the mother during pregnancy, liver blood flow in normal people, accounting for 35% of the heart’s blood displacement, after pregnancy, blood flow elsewhere in the body increases, liver blood flow drops to 28%. Another example is the high metabolism and increased nutritional consumption; during pregnancy the mother produces a large amount of sex hormones that need to be metabolized and inactivated in the liver, and the metabolism and detoxification of the fetus also depend on the maternal liver to complete, all of which increase the burden on the liver.
Hepatitis affects pregnancy: Chronic HBV infection can have a negative impact on pregnancy. It can increase the incidence of gestational diabetes, prenatal hemorrhage, preterm labor, and lower fetal Apgar scores. If liver function is severely abnormal, postpartum hemorrhage may easily occur, increasing the chance of infection and predisposing to preterm delivery, stillbirth, and neonatal asphyxia.
Management of hepatitis B infection in pregnancy
1, not pregnant with chronic hepatitis B patients of childbearing age, with antiviral indications should be actively antiviral treatment, and during treatment should take reliable measures to contraception to reduce the HBV load, liver function normal before pregnancy.
2, women with chronic HBV infection should have their liver function evaluated by a specialist in infection or hepatology before planning pregnancy. Those with HBV infection whose liver function is always normal can have a normal pregnancy; those with abnormal liver function can have a pregnancy if they return to normal after treatment and are rechecked normal for more than 6 months after stopping medication.
3. Patients with chronic hepatitis B who become pregnant during the course of oral antiviral drug treatment should be monitored regularly throughout pregnancy for liver function, HBV
DNA levels, assess the maternal liver condition, and continue treatment if the risks are fully informed and the pros and cons are weighed. A study showed that 38 women with chronic hepatitis B who had an unplanned pregnancy while taking lamivudine, who took lamivudine throughout pregnancy, did not find any complications after the birth of their child, and no cases of fetal injury or mother-to-child transmission occurred.
Therefore, it is recommended that women currently taking lamivudine may not stop taking the drug in the event of an unplanned pregnancy. The routine application of nucleoside (acid) analogues for the sole purpose of preventing mother-to-child transmission is not yet recommended for pregnant women with HBV infection (including HBeAg-positive).
4. Those who are found to be infected with HBV after pregnancy and diagnosed with chronic hepatitis B are generally not treated with antiviral therapy to minimize the exposure of therapeutic drugs to the fetus. However, for abnormal liver function and high HBVDNA levels, it is recommended to start antiviral therapy after 28 to 32 weeks of gestation and continue until delivery, or until 4 weeks postpartum before deciding whether to continue antiviral therapy according to the condition.
5, the choice of antiviral drugs during pregnancy: because common interferon and long-acting interferon have proliferation-inhibiting effects, such drugs are prohibited for use during pregnancy. According to the available evidence-based medical safety evidence, the choice of lamivudine, telbivudine and tenofovir is recommended as one of the three nucleoside analogues-.
Key points to reduce HBV infection in newborns
Reducing the rate of intrauterine infection and enhancing neonatal immunity to HBV are key to interrupting mother-to-child transmission. Early detection, diagnosis and treatment of pregnant women combined with a variety of measures to block the route of infection is the key to reducing HBV infection in newborns.
1, currently does not advocate routine antiviral therapy for all HBeAg positive pregnant women as a means to reduce mother-to-child transmission.
2, mother-to-child transmission, about 80% of the transmission during delivery, some studies have proposed that pregnant women with chronic HBV infection, delivery by cesarean section to reduce the delivery of newborns through the birth canal contact or inhaled blood, amniotic fluid or secretions containing HBV. However, most studies have shown that cesarean delivery cannot reduce mother-to-child transmission of HBV, and in clinical work, it is not recommended to choose cesarean delivery for blocking mother-to-child transmission of HBV.
3. It has been proposed that the application of hepatitis B high-valent immunoglobulin (HBIG) 2-3 times in late pregnancy for HBV-infected pregnant women can prevent intrauterine infection of the fetus, but most studies have shown that: the application of HBIG in late pregnancy has no effect on preventing mother-to-child transmission. Therefore, it is not necessary to apply HBIG to HBV-infected pregnant women in late pregnancy.
4, pregnant women with positive HBsAg, regardless of whether HBeAg is positive or negative, high or low HBVDNA levels, newborns must be timely injected HBIG and full vaccination against hepatitis B (0, 1, 6 months 3 doses program). HBIG needs to be used within 12 hours after birth (the earlier the better), the dose is greater than 100 units, intramuscular injection begins to work 15-30 minutes after The protective anti-HBs can be maintained for at least 42-63 days, by which time the body is already actively producing anti-HBs, so there is no need for a second injection of HBIG.
Currently, even if the recognized combined mother-infant blockade measures to achieve a protection rate of 80% to 95%, but there are still 10% of newborns failed to block.
Two major issues will be faced after delivery. One is whether to continue maternal antiviral therapy after delivery? Discontinuation of nucleoside analog therapy after delivery may lead to hepatitis virus rebound, therefore, HBVDNA levels should continue to be monitored closely after delivery and the decision to continue antiviral drug therapy should be made on a case-by-case basis. The second is whether it is possible to breastfeed the newborn after delivery?
In general, if the mother is not on antiviral therapy and the newborn has received timely active and passive immunoprophylaxis, breastfeeding will not increase the risk of HBV infection in the newborn; if the mother has received antiviral therapy, a cautious decision is needed whether to breastfeed because the safety of these drugs for the newborn during lactation exposure has not been proven.