Hepatitis B in Pregnancy
Hepatitis B in Pregnancy
Prevention of vertical transmission is critical because the majority of exposed infants become chronically infected. Transmission mainly occurs at the time of delivery or after birth, but rarely can occur in utero before. Several risk factors associated with infection in utero have been identified. Acquiring acute HBV during the third trimester is associated with a 60% to 90% vertical transmission rate. Threatened premature labor also is associated with an increased risk of infection, presumably from the mixing of maternal and fetal blood.
Amniocentesis does not increase the risk of vertical transmission. Mode of delivery is a controversial risk factor. During delivery, the child is exposed to vaginal secretions and possibly maternal blood, but there is no solid evidence that vaginal delivery increases the risk of vertical transmission when compared with cesarean delivery. Women with children infected with HBV are at increased risk of transmitting the virus to all subsequent children.
The most important risk factor for vertical transmission from mother to child is the mother's HBeAg status and HBV viral load. Without immunoprophylaxis, infants born to HBsAg-positive/HBeAg-positive mothers have a 70% to 90% chance of developing chronic HBV, but only a 10% to 20% chance if the mother is HBsAg positive/HBeAg negative.
Several studies have demonstrated that a maternal HBV viral load >10 copies per milliliter (20 million IU/mL) increases the risk of vertical transmission. This outcome has led many authors to conclude that it may be possible to reduce the risk of transmission of HBV by reducing the maternal level of viremia before delivery.
Risk of Mother-to-child Transmission
Prevention of vertical transmission is critical because the majority of exposed infants become chronically infected. Transmission mainly occurs at the time of delivery or after birth, but rarely can occur in utero before. Several risk factors associated with infection in utero have been identified. Acquiring acute HBV during the third trimester is associated with a 60% to 90% vertical transmission rate. Threatened premature labor also is associated with an increased risk of infection, presumably from the mixing of maternal and fetal blood.
Amniocentesis does not increase the risk of vertical transmission. Mode of delivery is a controversial risk factor. During delivery, the child is exposed to vaginal secretions and possibly maternal blood, but there is no solid evidence that vaginal delivery increases the risk of vertical transmission when compared with cesarean delivery. Women with children infected with HBV are at increased risk of transmitting the virus to all subsequent children.
The most important risk factor for vertical transmission from mother to child is the mother's HBeAg status and HBV viral load. Without immunoprophylaxis, infants born to HBsAg-positive/HBeAg-positive mothers have a 70% to 90% chance of developing chronic HBV, but only a 10% to 20% chance if the mother is HBsAg positive/HBeAg negative.
Several studies have demonstrated that a maternal HBV viral load >10 copies per milliliter (20 million IU/mL) increases the risk of vertical transmission. This outcome has led many authors to conclude that it may be possible to reduce the risk of transmission of HBV by reducing the maternal level of viremia before delivery.
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